Dual, single needle blood treatment system and method

ABSTRACT

A blood treatment system includes: (i) a dialysate circuit; (ii) a blood filter in fluid communication with the dialysate circuit; and (iii) an extracorporeal circuit in fluid communication with the blood filter, the extracorporeal circuit including a blood pump, a downstream line from the blood pump, an upstream line to the blood pump, a first patient access line, a second patient access line, a first valve arrangement fluidly communicating the first and second patient access lines to the downstream line, and a second valve arrangement fluidly communicating the first and second patient access lines to the upstream line.

PRIORITY

This application claims priority to and the benefit as a continuationapplication of U.S. patent application Ser. No. 11/773,634, filed Jul.5, 2007, entitled “Extracorporeal Dialysis Ready Peritoneal DialysisMachine”, now U.S. Pat. No. 8,512,553, the entire contents of which areincorporated herein by reference and relied upon.

BACKGROUND

The examples discussed below relate generally to medical fluid delivery.More particularly, the examples disclose systems, methods andapparatuses for the control of fluid flow in kidney failure treatmentsystems.

Due to various causes, a person's renal system can fail. Renal failureproduces several physiological derangements. The balance of water,minerals and the excretion of daily metabolic load is no longer possibleand toxic end products of nitrogen metabolism (urea, creatinine, uricacid, and others) can accumulate in blood and tissue.

Kidney failure and reduced kidney function have been treated withdialysis. Dialysis removes waste, toxins and excess water from the bodythat would otherwise have been removed by normal functioning kidneys.Dialysis treatment for replacement of kidney functions is critical tomany people because the treatment is life saving.

Hemodialysis and peritoneal dialysis are two types of dialysis therapiesused commonly to treat loss of kidney function. A hemodialysis (“HD”)treatment utilizes the patient's blood to remove waste, toxins andexcess water from the patient. The patient is connected to ahemodialysis machine and the patient's blood is pumped through themachine. Catheters are inserted into the patient's veins and arteries sothat blood can flow to and from the hemodialysis machine. The bloodpasses through a dialyzer of the machine, which removes waste, toxinsand excess water from the blood. The cleaned blood is returned to thepatient. A large amount of dialysate, for example about 80 to 120liters, is consumed to dialyze the blood during a single hemodialysistherapy. Hemodialysis treatment lasts several hours and is generallyperformed in a treatment center about three or four times per week.

Another form of kidney failure treatment involving blood ishemofiltration (“HF”), which is an alternative renal replacement therapythat relies on a convective transport of toxins from the patient'sblood. This therapy is accomplished by adding substitution orreplacement fluid to the extracorporeal circuit during treatment(typically ten to ninety liters of such fluid). That substitution fluidand the fluid accumulated by the patient in between treatments isultrafiltered over the course of the HF treatment, providing aconvective transport mechanism that is particularly beneficial inremoving middle and large molecules.

Hemodiafiltration (“HDF”) is another blood treatment modality thatcombines convective and diffusive clearances. HDF uses dialysate to flowthrough a dialyzer, similar to standard hemodialysis, providingdiffusive clearance. In addition, substitution solution is provideddirectly to the extracorporeal circuit, providing convective clearance.

Peritoneal dialysis uses a dialysis solution, also called dialysate,which is infused into a patient's peritoneal cavity via a catheter. Thedialysate contacts the peritoneal membrane of the peritoneal cavity.Waste, toxins and excess water pass from the patient's bloodstream,through the peritoneal membrane and into the dialysate due to diffusionand osmosis, i.e., an osmotic gradient occurs across the membrane. Thespent dialysate is drained from the patient, removing waste, toxins andexcess water from the patient. This cycle is repeated.

There are various types of peritoneal dialysis therapies, includingcontinuous ambulatory peritoneal dialysis (“CAPD”), automated peritonealdialysis (“APD”), tidal flow dialysis and continuous flow peritonealdialysis (“CFPD”). CAPD is a manual dialysis treatment. The patientmanually connects an implanted catheter to a drain, allowing spentdialysate fluid to drain from the peritoneal cavity. The patient thenconnects the catheter to a bag of fresh dialysate, infusing freshdialysate through the catheter and into the patient. The patientdisconnects the catheter from the fresh dialysate bag and allows thedialysate to dwell within the peritoneal cavity, wherein the transfer ofwaste, toxins and excess water takes place. After a dwell period, thepatient repeats the manual dialysis procedure, for example, four timesper day, each treatment lasting more than an hour. Manual peritonealdialysis requires a significant amount of time and effort from thepatient, leaving ample room for improvement.

Automated peritoneal dialysis (“APD”) is similar to CAPD in that thedialysis treatment includes drain, fill, and dwell cycles. APD machines,however, perform the cycles automatically, typically while the patientsleeps. APD machines free patients from having to manually perform thetreatment cycles and from having to transport supplies during the day.APD machines connect fluidly to an implanted catheter, to a source orbag of fresh dialysate and to a fluid drain. APD machines pump freshdialysate from a dialysate source, through the catheter, into thepatient's peritoneal cavity, and allow the dialysate to dwell within thecavity, and allow the transfer of waste, toxins and excess water to takeplace. The source can be multiple sterile dialysate solution bags.

APD machines pump spent dialysate from the peritoneal cavity, though thecatheter, to the drain. As with the manual process, several drain, filland dwell cycles occur during dialysate. A “last fill” sometimes occursat the end of APD, which remains in the peritoneal cavity of the patientuntil the next treatment.

Both CAPD and APD are batch type systems that send spent dialysis fluidto a drain. Tidal flow systems are modified batch systems. With tidalflow, instead of removing all of the fluid from the patient over alonger period of time, a portion of the fluid is removed and replacedafter smaller increments of time.

Continuous flow, or CFPD, systems clean or regenerate spent dialysateinstead of discarding it. The systems pump fluid into and out of thepatient, through a loop. Dialysate flows into the peritoneal cavitythrough one catheter lumen and out another catheter lumen. The fluidexiting the patient passes through a reconstitution device that removeswaste from the dialysate, e.g., via a urea removal column that employsurease to enzymatically convert urea into ammonia. The ammonia is thenremoved from the dialysate by adsorption prior to reintroduction of thedialysate into the peritoneal cavity. Additional sensors are employed tomonitor the removal of ammonia. CFPD systems are typically morecomplicated than batch systems.

It is known with PD therapy that the diffusive properties of theperitoneum degrade over time due at least in part to chronic exposure toglucose. While research has been done to find an alternative osmoticagent, glucose remains the industry standard. Accordingly, a need existsfor an improved PD therapy, which addresses the degradation of theeffectiveness of the diffusive properties of the peritoneum over time.

SUMMARY

The examples below describe systems that provide a improved dialysistreatment. The systems address the degradation of clearanceeffectiveness of PD due to the chronic exposure of the peritoneum toglucose. In one preferred implementation of the systems described below,the systems are tailored to be used by the patient at home. It should beappreciated however that the machines are not limited to at home use andcan instead be adapted for in-center or hospital use.

The systems in general provide an opportunity to the patient toalternate between PD, HD and/or HDF. Alternating therapies provides twoprimary advantages, namely, preserving maximum residual renal functionin PD and obtaining maximum urea clearance through HD or HDF. Thesystems provide “peritoneal rest” by enabling patients to perform HDover given intervals of time. Preliminary studies (⁽¹⁾: Tomo T. et al JArtif Organs, 2005; 8(2): 125-9; ⁽²⁾ Zareie M., et al, Nephrol DialTransplant, 2005 January; 20(1): 189-93; ⁽³⁾ Rodriquez A., AdvancedPeritoneal Dialysis, 2002; 18:7880) indicate that “peritoneal rest”after one or more PD treatment allows the peritoneum to heal at least tosome degree prior to the next exposure to glucose.

The systems provide a PD machine or cycler, which includes additionalhardware enabling HD to be performed in intervals as desired. One goalof the system is to provide a similar look, feel and mode of operationfor a patient that over time moves from early stages of end-stage renaldisease (exclusively or mainly PD through more advanced stages ofend-stage renal disease (exclusively or mainly HD). That is, the samemachine can be used to perform PD only, HD (HDF) only or to alternatebetween PD and HD (HDF).

In one embodiment, the PD/blood treatment cycler uses pneumatictechnology to control dialysate flow, such as the pneumatic technologysuccessfully employed in the HomeChoice® PD machine marketed by theassignee of this application. The pneumatic technology pumps dialysatein both PD and HD configurations. The PD cycler controls dialysate andultrafiltrate flow for both PD and HD therapies and also acts as themaster controller for a separate blood pump used for HD. In oneembodiment, the blood pump is provided separately from the PD cycler orunit, wherein the control unit of the PD unit controls the blood pumpvia a universal serial bus, serial, hard-dock or other type ofcommunication. The blood pump can be operated pneumatically using thesame technology as for dialysate flow or be driven via another type ofpumping, such as peristaltic pumping. The blood pump unit removes bloodfrom the patient and pushes it through a dialyzer, returning the bloodto the patient. The PD unit drives dialysate through the dialyzer, onthe outside of the dialyzer fibers, countercurrent to blood flow throughthe inside of the fibers in one embodiment.

In an alternative embodiment, the PD unit is configured to accept anadd-on blood pump. Here, a single disposable unit can be used for bothdialysate delivery and blood flow. Or, as shown below, separatedialysate and blood cassettes can be used. If the machine is used for PDthen the blood pump and blood cassette are not used. When the machineused for a blood treatment, such as HD, a blood pump module is added andthe blood cassette is used.

It should be appreciated that the HD/PD system is not limited to usingpneumatic control for pumping. The dialysate and/or the blood pump canbe driven mechanically or hydraulically for example. It is alsocontemplated to use peristaltic pumping to drive not only the blood butalso to pump dialysate. Here, the PD system can employ a separatevolumetric control device for the control of dialysate flow, e.g., oneor more balance chamber in combination with the pump, to meter the sameamount of dialysate to and from the dialyzer or peritoneum. A separatepump driven balance chamber is also used to meter a known amount ofspent fluid from the system, known as ultrafiltrate.

As discussed, it is contemplated to use different pumping technologiesto drive the blood. In one embodiment, the PD/blood treatment systemuses a peristaltic pump to drive the patient's blood. In an alternativeembodiment, blood is pumped, pneumatically, mechanically, hydraulicallyor any suitable combination thereof. The same technology that is used todrive the dialysate can be used to pump blood. Using the same pumpingtechnology to drive both dialysate and blood simplifies the controlschemes and accompanying apparatus necessary to control ultrafiltratefor both PD and HD.

The blood pumping unit, whether stand-alone or added to the dialysate orPD unit, includes pressure sensors positioned to sense arterial andvenous blood pressure. The blood unit also includes an air trap in atleast the return or venous line. The blood unit further includes one ormore valves or clamps to shut off the flow of blood in the event air isdetected, a leak is detected or upon an access disconnection from thepatient. One or more priming and/or rinseback device and method is alsoused, such as one that gravity feeds saline or to pushes dialysate intothe extracorporeal circuit.

The dialysate in both PD and HD needs to be heated. The PD/bloodtreatment system uses batch type heating in one embodiment, such as thatused in the HomeChoice® PD system. The PD/blood treatment system usesinline dialysate heating alternatively, such as resistive, inductive,convective or radiant inline heating (or any combination thereof).

In one HD configuration, the dialysate pumping unit pumps dialysate froma source bag to the dialyzer, which can be connected to the blood unit,and from the dialyzer into a recirculation bag. The recirculation bagenables spent dialysate to be reused. In one embodiment, the systempumps all fresh dialysate from one or more source bag, through thedialyzer, and to one or more recirculation bag. The system then reusesthe spent dialysate from the recirculation bags. This method removesurea advantageously when its concentration in the body is the highest,namely, at the beginning of treatment with fresh dialysate. That is, inthis counter-concentration arrangement, the freshest of the freshdialysate meets blood having the highest concentration of urea tomaximize the clearance of same. The spent dialysate cycle helps toremove other waste products, such as middle molecules, e.g., Beta-2Microglobulin that are typically slow to cross the dialyzer fibers. Themultiple pass use of dialysate allows the dialysate to become saturatedwith all of the toxins to be removed.

In one embodiment multiple supply bags are provided. A separaterecirculation bag captures spent fluid from a first source bag. Thefirst source bag is then used as the recirculation bag for the seconddialysate supply bag. The second dialysate supply bag is then used asthe recirculation bag for the third supply bag and so on. After allfresh solution has been pumped through the dialyzer once, the machine orsystem pumps the once-used dialysate from the recirculation bags,through the dialyzer, and back to the recirculation bags. If each ofthree supply bags holds six liters of fresh fluid, for example, the dualcirculation of the dialysate provides eighteen liters of fresh clearanceand eighteen liters of partially spent clearance.

The PD/blood treatment system is also configurable forhemodialfiltration (“HDF”), which combines diffusive and convectionclearance modes of HD and hemofiltration, respectively. Molecules suchas Beta-2 Microglobulin (“Beta-2”), do not diffuse through the dialyzeras efficiently as urea or creatinine for example. Because of its size,Beta-2 typically needs to be “dragged” across the dialyze membranes.Since the concentration of Beta-2 in the dialysate is likely not to benear equilibrium even after an initial entire eighteen liter circulationof fresh dialysate through the dialyzer, the partially-spent dialysateis used again in a convective way to remove Beta-2 in one embodiment.

In one embodiment, the PD/blood treatment system includes a substitutionpump, which introduces a substitution fluid directly into theextracorporeal circuit in front of, down stream of, or both upstream anddownstream of, the dialyzer. Here, diffusive and convective clearancesoccur simultaneously. This can be accomplished with an extra pump andseparate fluid holder or by “time sharing” the other pumps.

In one HDF implementation, the first eighteen liters is used diffusivelyto perform HD, the second eighteen liters is used convectively (in an HFmanner) to provide an overall HDF therapy. In the second run thePD/blood treatment system performs HDF using a “push-pull” method. Inthe push-pull method, the system increases the inlet dialysate pressureto be greater than that of the blood pressure, so that dialysate flowsatypically through the membrane walls of the fibers within the dialyzerand into the blood circuit of the HD system. The pressure on thedialysate side of the membranes is then reduced, pulling fluid from theextracorporeal circuit into the dialysate circuit. This cycle isrepeated a number of times using the last eighteen liters of dialysatein one implementation. Alternatively, a portion of the first eighteenliters or all thirty-two liters can be used to perform push-pull HF.

As mentioned, the first eighteen liters of HD clears urea primarily,while the eighteen liters of once-used dialysate used in the push-pullmanner removes middle molecules or ones that need to be dragged acrossthe dialyzer. It should be appreciated that pushing the dialysatethrough the membranes has the benefit of filtering the dialysate beforeit enters the extracorporeal circuit. The convective clearance comesfrom the fact that the once-used dialysate is still “cleaner” than fluidin the blood, for which the once-used dialysate is substituted. Thepush-pull method can be implemented in a dual needle or single needlearrangement as shown below.

Regarding single needle operation, another system of the presentdisclosure includes a dual, single needle arrangement. As describedherein, single needle systems are advantageous in one respect due totheir inherent and relative immunity to access disconnection problems.One drawback of typical single needle systems however is reducedclearances. Single needle systems are generally less efficient than dualneedle systems because single needle systems are either filling orremoving fluid to or from the patient at any given time. Dual needlesystems perform both functions simultaneously, increasing clearanceefficiency. Disclosed herein is a dual, single needle system in whichtwo single needle therapies are performed in essence at the same time.One therapy delivers fluid to the patient, while the other removes fluidfrom the patient, in an alternating single needle format, in oneembodiment.

In a further alternative embodiment, HDF is performed using a pair ofhigh flux dialyzers with a variable flow restriction placed between thetwo dialyzers. The variable flow restriction causes a dialysate pressureincrease in the upstream dialyzer, which is enough to force dialysateinto the extracorporeal circuit. This type of system is described inco-pending U.S. patent application Ser. No. 10/982,170, entitled “HighConvection Home Hemodialysis/Hemofiltration And Sorbent System”, filedNov. 4, 2004, owned by the assignee of the present application, theentire contents of which are hereby incorporated by reference.

The systems include a control scheme and corresponding user interfacethat decides which treatment modality to perform manually automatically(e.g., according to a doctor's prescription). For example, if determinedautomatically, the machine upon power-up recalls which modality is to beperformed and prompts the patient or user accordingly. If determinedmanually (e.g., patient or caregiver determines) or the patient orcaregiver can enter the information at the start of treatment accordingto a prescribed chart or calendar. The machine again prompts the patientaccordingly.

It is therefore an advantage of the present disclosure to provide acombination PD/HD, PD/HF or PD/HDF system.

Another advantage of the present disclosure is to provide a singlesystem that can manually or automatically perform different modalitiesof dialysis as desired, either over a same therapy or differenttherapies.

A further advantage of the present disclosure to provide a modularPD/blood treatment system, which enables a modular blood pumping unit tooperate with a stand alone PD unit.

It is still another advantage of the present disclosure to provide animproved single need dialysis treatment.

Additional features and advantages are described herein, and will beapparent from, the following Detailed Description and the figures.

BRIEF DESCRIPTION OF THE FIGURES

FIG. 1 is a schematic diagram of one embodiment of a PD/blood treatmentsystem in which spent dialysate is sent to a drain.

FIG. 2 illustrates another embodiment for the PD/HD system, which uses aperistaltic pump based blood unit in combination with a dialysate unitthat pumps from a plurality of supply bags into a plurality ofrecirculation bags.

FIG. 3 illustrates another embodiment for the PD/HD system, which usesthe same type of pumping for both the pumping of dialysate and blood.

FIG. 4 illustrates a further embodiment of the PD/HD system, in whichdialysate is pumped and metered using a peristaltic pump in combinationwith at least one balance chamber.

FIG. 5 illustrates yet another PD/HD system in which a weight scale isused to control volume of dialysate delivered and ultrafilteration.

FIG. 6 illustrates a PD/HDF system in a first valve state configured topush dialysate into the extracorporeal circuit in a “push-pull”hemo(dia)filtration (“HDF”) modality.

FIG. 7 illustrates a PD/HDF system in a second valve state, in whichdialysate is pulled from the extracorporeal circuit into the dialysatecircuit to perform a pull portion of the “push-pull” HDF.

FIG. 8A illustrates a single needle PD/“push-pull” hemo(dia)filtrationsystem.

FIGS. 8B to 8D illustrate three stages of dialysate delivery for thesingle needle PD/“push-pull” hemo(dia)filtration system of FIG. 8A.

FIG. 9A illustrates a dual-single needle PD/“push-pull”hemo(dia)filtration system in a first valve state.

FIG. 9B illustrates a dual-single needle PD/“push-pull”hemo(dia)filtration system in a second valve state.

FIG. 10 illustrates a first alternative PD/HDF system for performing HDFusing membrane pumps and a variable restriction placed between a pair ofhigh flux dialyzers.

FIG. 11 illustrates a second alternative PD/HDF system for performingHDF using peristaltic pumps, a pair of balance chambers and a variablerestriction placed between a pair of high flux dialyzers.

FIG. 12A schematically illustrates the logistics involved with thecontrol architecture for the PD systems having blood treatment optionsdescribed herein.

FIG. 12B schematically illustrates the disposables involved with thecontrol architecture for the PD systems having blood treatment optionsdescribed herein.

FIG. 12C schematically illustrates various embodiments for powerdistribution schemes for the control architecture of the PD systemshaving blood treatment options described herein.

FIG. 12D schematically illustrates one embodiment of the softwaremodules used for the control architecture of the PD systems having bloodtreatment options described herein.

FIG. 12E schematically illustrates one embodiment of a single PD/HDdistribution of software modules used for the control architecture ofthe PD systems having blood treatment options described herein.

FIG. 12F schematically illustrates one embodiment of a dual PD/HDdistribution of software modules used for the control architecture ofthe PD systems having blood treatment options described herein.

FIGS. 13A and FIG. 13B are perspective views of one embodiment of acombined PD/HD system with dialysate and blood cassettes for a bloodtreatment therapy not loaded and loaded, respectively.

FIGS. 14A and 14B are perspective views of one embodiment of a dialysateside cassette for the system of FIGS. 13A and 13B.

FIG. 15 is a perspective view of one embodiment a blood cassette for thesystem of FIGS. 13A and 13B.

FIGS. 16A and 16B are perspective views (cassette removed and loaded,respectively) of the combined PD/HD system of FIGS. 13A and 13B, inwhich the blood treatment apparatus is removed so that the system is nowconfigured for PD.

FIGS. 17A and 17B are perspective views of a PD dialysate cassette thatcan be loaded into the area of the PD/HD system of FIGS. 13A, 13B, 16Aand 16B.

FIGS. 18A to 18E are perspective views of a PD/HD system in which theblood unit or module (FIG. 18C) is provided as a separate device, whichcan be docked to (FIGS. 18D and 18E) the PD unit (FIGS. 18A and 18B).

FIG. 19 is a schematic flow diagram illustrating one operationalsequence for the PD/blood treatment systems described herein.

FIG. 20 is a schematic flow diagram illustrating a first alternativeoperational sequence for the PD/blood treatment systems describedherein.

FIG. 21 is a schematic flow diagram illustrating a second alternativeoperational sequence for the PD/blood treatment systems describedherein.

FIG. 22 is a schematic flow diagram illustrating a third alternativeoperational sequence for the PD/blood treatment systems describedherein.

DETAILED DESCRIPTION PD/HD Systems

Referring now to the drawings and in particular to FIG. 1, oneembodiment for a combined PD/HD system is illustrated by system 10.System 10 includes a peritoneal dialysis (“PD”) machine or unit 20. PDunit 20 as discussed herein is sued interchangeable for PD, HD, HF andHDF. For ease of description, however, unit 20 is generally referred toherein as PD unit 20.

Machine or unit 20 can be any suitable PD machine or unit, such as theHomeChoice® automatic peritoneal dialysis (“APD”) machine, marketed bythe assignee of this application. PD unit 20 includes a housing 22.Housing 22 houses components necessary to perform peritoneal dialysis,such as pumps 24 a and 24 b. Pumps 24 a and 24 b in the illustratedembodiment are pneumatically operated cassette-based pumps. TheHomeChoice® machine pumps use a fluid management system (“FMS”) tocontrol the volume of fluid and ultrafiltrate removed from the patientaccordingly. FMS is described for example in U.S. Pat. No. 5,431,626(“the '626 Patent”), entitled “Liquid Pumping Mechanisms For PeritonealDialysis Systems Employing Fluid Pressure”, the entire contents of whichare incorporate herein by reference. As discussed in detail below, PDunit 20 can employ any suitable type of pump and valve actuation.

The '626 Patent describes other components located within or on housing22 necessary for dialysate, such as the pneumatic pump and valveactuators, heater actuator and controller. The control unit of PD unit20 is shown schematically in FIG. 1 as master controller 26. Mastercontroller 26 is configured with the software and processing needed torun PD unit 20 in a peritoneal dialysis mode. The '626 Patent describesone possible control of PD unit 20. Master controller 26 is alsoconfigured to communicate with and control a delegate controller 46located within a separate blood pump unit 40. The master/delegatecontrol of PD unit 20 and blood pump unit 40 is discussed in detailbelow.

Blood pump unit 40 as described herein is used interchangeably for HD,HF, HDF. For ease of description, however, blood pump unit 40 isgenerally referenced to herein as HD unit 40.

As discussed in the '626 Patent, to perform PD dialysate unit 20operates with a disposable fluid cassette. The disposable fluid cassetteconnects fluidly to a number of fluid line, such as one or more supplylines, a patient line, and a drain line. The cassette is shownschematically in FIG. 1 as cassette 30 a for PD or cassette 30 b for HDor HDF (referred collectively as HD cassette 30 b for simplicity).Cassette 30 a is dedicated solely for PD use and can be the HomeChoice®machine cassette for example. HD cassette 30 b is dedicated to HD orHDF.

Generally, automated peritoneal dialysis is done on a batch orsemi-batch basis, in which fresh fluid is pumped to the patient'speritoneum and allowed to dwell within the peritoneal cavity beforebeing pumped from the peritoneal cavity to drain. Other PD modalitiessuch as tidal flow remove a portion of the fluid dwelling within theperitoneal cavity and replace that portion with a fresh portion. Herestill, only a single catheter is needed because at any one time fluid iseither being sent to or drawn from patient 14. In such a case, a singledialysate inlet/outlet line 38 (shown in FIGS. 1 to 8A) is used insteadof separate inlet and outlet lines discussed below.

It is contemplated for system 10 to perform CFPD, which includes asimultaneous filling and draining of patient 14. Here, separate lines 38a and 38 b lead from PD cassette 30 a to patient 14. Or, a single duallumen catheter is used. In either case, PD cassette 30 a provides twopatient ports, which are akin to dual ports dialyzer used with HDcassette 30 b to connect it fluidly to dialysate outlet and inlet lines38 a and 38 b, respectively.

Cassette 30 b is configured for HD. It differs from cassette 30 a atleast in that the “patient” for HD cassette 30 b is a dialyzer 42, whichrequires outlet line 38 a and inlet line 38 b. Certain flowpaths of HDcassette 30 b are also modified.

In one embodiment PD cassette 30 a and HD cassette 30 b are sized thesame, so that each can be placed alternatively into the same dialysatemachine 20. This involves structuring the flowpaths of both cassettes sothat the pumping chambers and valve chambers of both cassettes 30 a and30 b can operate with the same pump and valve actuators of PD unit 20.It is also contemplated to structure and configure the pump and valveactuators of PD unit 20, so that cassette 30 a and 30 b can be moreeasily configured to have the same shape, valve operation and pumpoperation. FIGS. 14A, 14B, 17A and 17B below illustrate suitableconfigurations for cassettes 30 a and 30 b, which share the same shape,valve and pump actuation.

As mentioned, HD cassette 30 b in one embodiment is loaded into the samearea of PD unit 20 as PD cassette 30 a when performing a bloodtreatment. In an alternative embodiment, PD cassette 30 a and HDcassette 30 b are mounted in a different location of housing 22 of PDunit 20. The two cassettes 30 a and 30 b can then have different sizesand be configured so that valve actuation and pump actuation take placeseparately. An advantage here would be to incorporate the movement ofblood into HD cassette 30 b.

In any case, a supply line 32 is connected fluidly from fluid supply 12to cassette 30 a/30 b. With PD a to/from patient line 38 is connectedfluidly between PD cassette 30 a and patient 14. Further, a drain line36 is connected fluidly between cassette 30 a/30 b and drain 16.Cassette 30 a/30 b operates with pump and valve actuators, such as thepneumatic actuators described in the '626 Patent.

As seen in FIG. 1, HD cassette 30 b of PD unit 20 of system 10communicates fluidly with a dialyzer 42 via to-dialyzer line 38 a andfrom-dialyzer line 38 b, which are connected to an HD cassette 30 bloaded in PD unit 20.

Cassettes 30 a and 30 b each connect to a drain line 36 and one or moresupply line 32. Depending on the type of heating being used, cassettes30 a and 30 b include to-and from-heater lines if the cassettes operatewith a stand alone, e.g., inline heater. Alternatively, the fluidheating pathway of the inline heater is integrated into cassette 30 a/30b, such that additional to- and from-heating ports are not needed. In afurther alternative embodiment, batch heating is used, similar to thatdescribed in the '626 Patent, wherein dialysate can be gravity fed froma source 12 into a heater bag, which for example can be placed on top ofPD unit 20. Supply line 32 then extends from the heater bag to cassette30 a/30 b.

PD cassette 30 a and HD cassette 30 b include common features as alludedto above. For example, both can be made of the same material, which caninclude for example a rigid plastic piece defining the flow paths andvalve seats. The rigid, plastic piece is then sealed via a thin flexiblefilm or membrane, which is flexed to open and close valves and to pumpfluid through pump chambers of pumping portions 24 a and 24 b ofcassette 30 a/30 b. Also, cassette 30 a/30 b can have an air removalapparatus, such as air traps or air vents. Copending U.S. patentapplication Ser. No. 11/530,842 (“the '842 app”), entitled “MedicalFluid System With Flexible Sheeting Disposable Unit”, filed Sep. 11,2006, assigned to the assignee of the present application, the entirecontents of which are incorporated by reference discloses purelyflexible cassettes, which can be used for cassettes 30 a/30 b.

A separate blood cassette 44 in one embodiment is used with HD unit 40.Blood cassette 44 in one embodiment is formed integrally with HDcassette 30 b in a single overall cassette. This is done for examplewhen PD unit 20 and HD unit 40 are provided within a single housing orenclosure. In an alternative embodiment, blood cassette 44 is physicallyseparate from HD dialysate cassette 30 b. This is the case when HD unit40 is housed in a separate enclosure and when HD cassette 30 b and PDcassette 30 a are meant to interchangeably mate with PD unit 20. In afurther alternative embodiment, blood cassette 44 can be separate fromHD dialysate cassette 30 b, but wherein both are placed within a samehousing or enclosure containing HD unit 40 and PD unit 20.

Blood cassette 44 is connected to a plurality of extracorporeal tubes.For example, blood cassette 44 is connected to a to-dialyzer line 48 aand a from-dialyzer line 48 b. Blood cassette 44 is also connected toarterial line 52 and venous line 54. As seen, arterial line 52 is alsocoupled operably to a peristaltic pump 50. Peristaltic pump 50 operateswith valves located within blood unit 40 to pump blood from patient 14,through arterial line 52, into blood cassette 44, out throughto-dialyzer line 48a, through the inside of hollow fibers withindialyzer 42, through from-dialyzer line 48 b, back into blood cassette44, through venous line 54, sending cleaned blood back into patient 14.

Blood pumped through dialyzer 42 travels inside a plurality ofhollow-fiber membranes located within dialyzer 42. PD unit 20 pumpsdialysate through to-dialyzer line 38 a into dialyzer 42 wherein thedialysate passes along the outside of the hollow-fiber membranes as isknown in the art, returning through from-dialyzer line 38 b to HDcassette 30 b, after which the once-used dialysate is sent via drainline36 to drain 16 in system 10 of FIG. 1.

Blood cassette 44 is also valved and configured to connect fluidly withand operate a prime and rinseback line 28, which receives fresh solutionfrom source 12. The fresh solution is used to flush to- and from-dialyzer lines 48 a and 48 b, the extracorporeal portion of dialyzer 42and arterial and venous lines 52 and 54, respectively, in a primesequence or blood rinseback sequence.

In one rinseback sequence, blood pump 50 is run in two directions, onedirection to pull fresh solution through line 28, cassette 44, througharterial line 52, pushing any blood remaining in the arterial line backinto patient 14. Next, blood pump 50 is reversed, pumping fluid fromcassette 44, through venous line 54, pushing any blood remaining invenous line 44 back to patient 14.

In one prime sequence (performed before therapy starts), arterial line52 and venous line 54 are connected together to form a closed loop. Pump50 operates unidirectionally or bi-directionally to fill theextracorporeal lines with fresh fluid from line 28 completely beforearterial line 52 and venous line 54 are connected to patient 14.

In an alternative embodiment, separate prime and rinseback line 28 isnot used. Instead fresh dialysate from source 12 is driven via PD unit20 into dialyzer 42, through the open pores of the membranes locatedwith dialyzer 42, through to- and from-dialyzer lines 48 a and 48 b,into cassette 44, and then selectively through arterial and venous lines52 and 54, as needed, to perform a prime or rinseback.

HD unit 40 includes other apparatuses to ensure safe pumping of thepatient's blood through the extracorporeal circuit. For example, HD unit40 includes safety clamps that occlude arterial line 52 and venous line54 upon an alarm. Unit 40 also includes an air trap or an air vent invenous line 54 for example, which prevent(s) air from being delivered topatient 14. Extracorporeal apparatuses are shown in more detail below inconnection with FIGS. 10 and 11.

HD unit 40 in one embodiment has its own user interface, which showsblood parameter settings and readings, such as blood pressure readings,blood temperature readings, transmembrane pressure and the like. Theblood unit user interface can also be used to enter blood parametersettings through the use of a touch screen overlay or membrane switchesfor example. The sensors necessary to read blood parameters are providedwithin HD unit 40. In an alternative embodiment, the sensor informationis sent via a data line or bus 60 to PD unit 20 for display. The bloodsettings are here made at the user interface of PD unit 20.

As seen in FIG. 1, HD unit 40 includes a controller 46, which can be oneor more printed circuit board (“PCB”) housing a microprocessor, readonly memory (“ROM”) and random access memory (“RAM”). Alternatively,controller 46 includes one or more application specific integratedcircuit (“ASIC”). Controller 46 communicates via data line or bus 60with control unit 26 of PD unit 20. In an embodiment, controller 26 islikewise a PCB, which includes a microprocessor, ROM and RAM. Controlunit 26 can be a series of printed circuit boards or otherwise include asupervisory processor that runs one or more delegate processor ordelegate PCB. The supervisory role of control unit 26 applies also tothe interface between PD unit 20 and HD unit 40, wherein controller 46is configured as a delegate or subservient controller to the supervisorycontrol unit 26 of PD unit 20. For example, PD unit 20 in one embodimentincludes a safety controller, which monitors the safety and performanceof components within PD unit 20 as well as within HD unit 40.

Data line or bus 60 is any suitable type of data transmission, such as auniversal serial bus (“USB”), serial, hard-docked or wirelesstransmission. In a wireless embodiment, blood controller 46 communicateswith dialysate control unit 26 via radio frequency (“RF”), encoded RF,secure Bluetooth technologies microwave, or other type of wirelesscommunication. For example both blood controller 46 and dialysatecontrol unit 26 can power wireless transceivers that allow two units tocommunicate back and forth. As described above, HD unit 40 in oneembodiment is combined in the same housing with PD unit 20, in whichcase controller 46 and control cards for control unit 26 are pluggedinto a data bus 60.

Controller 46 sends and receives data from control unit 26. For example,Controller 46 can send blood pump speed, blood temperature, bloodpressure, air detection, access disconnection and other information tocontrol unit 26, which confirms that the information is within safeoperating limits and also confirms that PD unit 20 itself is functioningproperly to deliver dialysate to dialyzer 42. In the event that controlunit 26 receives any information that either a function of blood unit 40or PD unit 20 is in an alarm state, control unit 26 sends a messagealong data transmission 60 to controller 46. Controller 46 in turn shutsdown blood pump 50 and closes the appropriate valves, either withinblood cassette 44 or via a separate occluder to clamp arterial line 52and venous line 54. The blood valves or clamps are configured to closeupon a power off condition, providing fail-safe operation

Referring now to FIG. 2, an alternative PD/HD system 70 is illustrated.System 70 includes many of the same components described above inconnection with system 10, wherein such like components have the samealternative embodiments and are numbered the same. System 70 includes anumber of differences however. For example, in system 10 dialysate pumps24 a and 24 b (which are described as being of any of plurality ofdifferent types suitable for controlling the amount of dialysatedelivered to and removed from dialyzer 42 and also for controlling anamount of ultrafiltrate removed from the patient 14) have been describedprimarily as being of the type from '626 Patent using the FMStechnology. In system 70, pumps 24 a and 24 b are volumetric or membranepumps. Membrane pumps 24 a and 24 b in system 70 each have a membrane72, which moves back and forward within a chamber having a known volume.Thus with each stroke of membrane 72, a known volume of fluid is pumpedto dialyzer 42 as illustrated.

Two or more membrane pumps 24 a to 24 b can be provided to provide an atleast substantially continuous flow of fluid to and from dialyzer 42.That is, while one membrane pump 24 a or 24 b is in a fill stroke, theother is in a reload stroke. Membrane pumps 24 a and 24 b alternate inthis manner. Membrane pumps 24 a and 24 b can also be used to removeultrafiltrate. A separate membrane pump (not illustrated) is provided,in another embodiment for removing ultrafiltrate. The membrane pumpsensure that a precise amount of fluid is delivered to and removed frompatient 14 for PD and dialyzer 42 for HD and is removed as ultrafiltrateby totaling the strokes of the dialysate and ultrafiltrate membranepumps.

Suitable pneumatically and mechanically driven medical fluid pumps anddiaphragms therefore are described in commonly owned U.S. patent Ser.No. 10/335,646, entitled, “Systems, Methods And Apparatuses For PumpingCassette-Based Therapies”, filed Dec. 31, 2002, the teachings of whichare incorporated herein by reference. The pumps and pumping technologiesdescribed in commonly owned U.S. patent Ser. No. 10/155,754, entitled“Medical Fluid Pump”, filed May 24, 2002, are also incorporated hereinby reference.

FIG. 2 also shows that blood cassette 44 of HD unit 40 includes valvesor clamps, such as clamp 74, which for example closes venous line 54upon an error condition or within a predetermined blood flow sequence.Blood cassette 44 also includes an air collection and removal apparatus76, which traps air and/or enables air to vent to atmosphere.

Another main difference between system 70 and system 10 is that multiplesupply bags 12 a to 12 c and a separate recirculation bag 18 areprovided. In system 70, once-used dialysate is delivered from dialyzer42 to recirculation bag 18 instead of to drain 16 as shown in connectionwith FIG. 10. Capturing once-used dialysate in recirculation bag 18allows system 70 to reuse that solution. To that end, it is known thatthe concentration of urea in a person with renal failure is highest atthe beginning of treatment and that it is recovered most efficiently viadiffusion (clearance mode of HD). System 70 is accordingly configured inone embodiment to pump all fresh dialysate from supply bags 12 a through12 c to dialyzer 42 advantageously before recycling any solution. Thiscauses an optimum removal of urea.

In one embodiment, PD unit 20 pumps fresh dialysate from initial sourcebag 12 a via HD cassette 30 b to dialyzer 42 and pumps the resultingonce-used solution into recirculation bag 18. When the pumping of freshsolution from solution bag 12 a is complete, solution bag 12 a is thenused as the second recirculation or storage bag. Next, fresh solution ispumped from second solution bag 12 b, through dialyzer 42 and back intofirst dialysate solution bag 12 a (second storage bag). When thatpumping is completed, solution is then pumped from third supply bag 12c, through dialyzer 42, back into second supply bag 12 b (thirdrecirculation bag).

System 70 then begins its recirculation cycle and causes the once-usedsolution to be pumped for example from recirculation bag 18, throughdialyzer 42, and into fourth recirculation bag 12 c. Once-used solutionis then pumped from recirculation bag 12 a through dialyzer 42, intorecirculation bag 18. Finally, once-used solution is pumped from spentsupply bag 12 b, through dialyzer 42, into recirculation bag 12 a. Thisscenario enables system 70 to pass, e.g., eighteen liters of dialysatethrough dialyzer 42 (assuming six liter supply bags) two times, oncewith fresh dialysate and again with once-used dialysate. Passing theonce-used dialysate through dialyzer 42 a second time helps to removemore of certain larger molecules, such as beta-2 microglobulin, that arenot diffused completely with the first pass. It should be appreciatedthat the twice-used dialysate can be recirculated a third or fourth timeif needed. Recirculation can be used with the FMS pumping of system 10and any other pumping system described herein.

Also, each of the systems described herein can employ a sorbent and/orcarbon filled cartridge 62 that removes at least some of the waste fromthe once-used dialysate. Such one or more cartridge 62 is shown as beinghoused by PD unit 20 and in fluid communication with dialysate returnline 38 b. In this configuration, the cleansing chemicals and materialsare provided in a quantity sufficient to clean multiple therapies bothof one-used dialysate. PD unit 20 in on embodiment delivers a cartridgereplacement message on its user interface after so many strokes of pumps24 a and/or 24 b, number of therapies performed, number of days ofservice or any combination thereof.

In an alternative embodiment, cartridges 62 is provided as part of APDcassette 30 b, here in a quantity sized for one treatment's worth offluid. In a further alternative embodiment, the chemicals and materialsare provided in recirculation bag 18 and/or in a compartment of supplybags 12 a to 12 c separated by an automatically separated frangibleseal.

Suitable chemicals and cleaning materials for cartridge 62 include amaterial that is capable of non-selective removal of solutes from thetherapy fluid that have been removed from the patient during therapy.The material includes a suitable sorbent material, such as carbon,activated carbon and/or other like material that can be contained withina, e.g., plastic, cartridge 62, in a medically safe manner. In anembodiment, the non-selective removal of solutes from the dialysate canbe used, on its own, to clean the dialysate such that a more effectiveremoval of solutes and excess water from the patient can occur uponreuse of the dialysate.

In an embodiment, cartridge 62 provides materials in addition to thosethat can non-selectively remove solutes from the dialysate. Additionalmaterials include, for example, materials that can selectively removecertain solutes or the like from solution, such as, a binder materialcapable of selectively removing urea or a binder material capable ofselectively removing phosphate, for example.

In general, the binder materials chemically bind the solutes, such asurea, to remove them from the dialysate or other suitable fluid mediumas described below in greater detail. This process does not result inthe release of harmful substances as reaction by-products as compared toan enzymatic process. For example, urease is known to enzymaticallyconvert urea into ammonia. However, ammonia should then be removed fromthe dialysate prior to reintroduction of the fluid for PD, HD or HDF.With binder materials, the dialysate can be reintroduced without furtherprocessing of the dialysate as a result of the binder process. Materialscapable of selective removal of solutes, particularly urea, can be usedto enhance the cleaning efficiency of cartridge 62, so that the originaleighteen liters of dialysate is restored closer to its “fresh” state.

Cleaning cartridge 62 can include materials that can selectively removesolutes from solution, such as binder materials, for example polymericmaterials that are capable of removing nitrogen-containing compounds,such as urea, creatinine, other like metabolic waste and/or the like insolution. In general, these types of materials contain a functionalgroup(s) that chemically binds with urea or other like solutes. Forexample, U.S. Pat. Nos. 3,933,753 and 4,012,317, each incorporatedherein by reference, disclose alkenylaromatic polymers containingphenylglyoxal that can function to chemically bind urea. In general, thephenylglyoxal polymeric material is made via acetylation performed in,for example, nitrobenzene followed by halogenation of the acetyl groupand treatment with dimethylsulfoxide as disclosed in U.S. Pat. Nos.3,933,753 and 4,012,317. Another example of a polymeric material that iscapable of selectively removing solutes, such as urea, from solutionincludes polymeric materials that contain a tricarbonyl functionalitycommonly known as ninhydrin as disclosed in U.S. Pat. No. 4,897,200,incorporated herein by reference.

Cleaning cartridge 62 can also include a number of components inaddition to the materials capable of removing solutes from thedialysate. For example, cleaning cartridge 62 may have the capability toremove all or a portion of electrolytes, such as sodium, potassium, orthe like, from the dialysate solution. In this case, an additionalsource of electrolytes in solution may be needed to replenish thedialysate after it has been cleaned. Cartridge 62 may also be configuredto release bicarbonate or the like into the system depending on the typeof cleaning material used. This can facilitate pH regulation of thedialysate. As necessary, cartridge 62 may include a filter to preventproteins, particulate matter or like constituents from leaching orexiting from the cartridge and into the dialysate.

Molecules such as beta-2 micro microglobulin are known not to diffusethrough a dialyzer as efficiently as urea or creatinine due to theirsize. These molecules can be removed more efficiently by dragging themacross the membrane. The systems described herein take advantage of theconvective potential remaining in the once-used (and potentiallycleaned) dialysate. The once-used dialysate is used convectively, e.g.,in an HF model as described below in FIGS. 6 and 7 to drag largermolecules such as beta-2 micro globulin across the dialyzer.

Referring now to FIGS. 3 to 5, systems 80, 90 and 100, respectively,each show different types of pumping technologies that may used in thePD/blood systems to control dialysate and ultrafiltrate flow and volume.Systems 80, 90 and 100 are each shown with the recirculation bagconfiguration including supply bags 12 a to 12 c and recirculation bag18 as illustrated in connection with system 70 of FIG. 2. It should beappreciated however that systems 80, 90 and 100 can alternatively pumpspent dialysate to drain 16.

System 80 of FIG. 3 shows that the peristaltic blood pump 50 of systems10 and 70 is replaced by a pair of volumetric or membrane pumps 50 a and50 b. Membrane pumps 50 a and 50 b use the same pumping technology asdialysate membrane pumps 24 a and 24 b, each of which include a membrane72 as described above. The import here is that the same pumpingtechnology is used in both PD unit 20 and HD unit 40. This enables thecontrol function of the PD/blood system to be simplified andstandardized. For example, the strokes of the dialysate and blood pumps24 a/24 b and 50 a/50 b, respectively, can be synchronized, such that asame set of end-of-stroke sensors can be used for each. In oneembodiment, the FMS pumps of the HomeChoice® machine are used for bothdialysate and blood pumping. Here, the same software can be used tocalculate the amount of fluid delivered for both PD unit 20 and HD unit40. The main difference between the operation of the PD unit whenperforming HD is that, the pumps operate continuously and against higherbackpressures compared to the intermittent pumping and lowerbackpressures of PD.

System 90 of FIG. 4 illustrates a further alternative pumpingtechnology, which combines one or more peristaltic dialysate pump 24with a pair of balancing chambers 92 and 94. Balance chambers 92 and 94can be housed in dialysate cassette 30 a and 30 b as disclosed in thepatent application cited above. Balancing chambers 92 and 94 eachinclude a membrane 72 that isolates and separates the fluid on oppositesides of the membrane 72. Although not illustrated, in one preferredembodiment two peristaltic dialysate pumps 24 are provided, one drivingfresh and the other driving spent or once-used fluid, respectively, toeither sides of both balancing chambers 92 and 94, so that the sameexact amount of fluid is delivered to and removed from dialyzer 42 uponeach stroke of balance chambers 92 and 94.

In one embodiment, each balancing chamber 92 and 94 includes twocompartments, one termed a “pre-dialyzer” compartment and the other a“post-dialyzer” compartment. Each opposing “pre” and “post” compartmentof a chamber is separated by a flexible diaphragm. Electrically,mechanically or pneumatically actuated valves control the filling andemptying of each compartment. Also, the “pre” compartments arealternately filled and discharged and the “post” compartments arealternately filled and discharged. Filling a “pre” compartment causes adischarge of a corresponding and opposing “post” compartment,respectively. Filling a “post” compartment causes a discharge of acorresponding and opposing “post” compartment.

Since the volumes of opposing “pre” and “post” compartments of the twochambers are equal, the system volumetrically balances the flow ofdialysate to and from the dialyzer. One benefit of this volumetricallycontrolled system is that dialysate flow to and from the dialyzer can beaccurately balanced over a wide range of flowrates.

In an embodiment, a third UF balancing chamber (not illustrated) isprovided and driven by a spent peristaltic dialysate pump 24 dedicatedto spent fluid, which drives spent fluid to both sides of UF chamber inaddition to the spent compartments of balancing chambers 92 and 94. Thethird balancing chamber is used to meter ultrafiltrate. Here, instead ofalternating fresh and spent pump cycles, the third UF balancing chamberreceives spent dialysate on both sides of its membrane 72, which drivesa known amount spent dialysate as UF to drain 16 or to a recirculationbag 12 a to 12 c or 18.

The configuration of system 90 is advantageous in one respect becauseperistaltic pump 24 is a low cost and safe medical fluid pumpingtechnology. The drawback of a peristaltic pump is generally consideredto be its accuracy. Balancing chambers 92 and 94, however, provide theaccuracy needed to ensure that a prescribed amount of ultrafiltrate isremoved from the patient both PD or HD.

Referring now to FIG. 5, a further alternative pumping technologysuitable for use with the PD/blood systems is illustrated by system 100.System 100 weighs the dialysate delivered and ultrafiltrate removed. Theweighing system uses a pan or container 103 that holds one or more orall of supply bags 12 a to 12 c and recirculation bag 18. Container 103is coupled to a weight scale 105, which includes a load cell 106configured to send a signal to dialysate control unit 26. The accuracyof the weight system enables the simpler, less accurate but safeperistaltic dialysate pump 24 to be used. One drawback with weighingsystems is the need to weigh each of supply bags 12 a to 12 c and drainbags, such as drain 16 or the recirculation bag 18 discussed above. Onegravimetric dialysis system overcoming this particular problem isdisclosed in U.S. patent application Ser No. 11/422,267, filed on Jun.5, 2006, entitled “Dynamic Weight Balancing Of Flow In Kidney FailureTreatments”, assigned to the assignee of the present application, theentire contents of which are incorporated herein by reference.

As discussed above, certain molecules, such as beta-2 microglobulin, areremoved more effectively via a convective clearance. One way ofobtaining the benefits of both diffusive and convective modes oftransport is via hemodiafiltration (“HDF”), which combines the diffusiveclearance of dialysis and the convective clearance of hemofiltration. Ingeneral, hemofiltration involves the injection of a substitution fluidinto the extracorporeal circuit directly (as opposed to the outside ofdialysis membranes). Waste and toxins are removed from the blood liquidvia a dilution or convection process, in which cleaned fluid isintroduced into the patient's blood stream and clean-mixed-with toxicladen blood liquid is removed. Over time this process cleans the blood.

One way for the systems herein to perform hemodiafiltration is toconnect a substitution fluid line to the to-dialyzer line 48 a(predilution hemofiltration) or from-dialyzer line 48 b (post dilutionhemofiltration). This enables dialysate to be delivered to dialyzer 42as discussed above and at the same time substitution fluid to bedelivered to the extracorporeal circuit directly. A net amount ofultrafiltration is removed from the system through dialysate return line38 b from dialyzer 42 as discussed above with pure HD. The combineddiffusive and convective clearance makes are generally thought to be onevery effective way of treating a patient with kidney failure.

A separate pump in one embodiment is provided to pump the replacementfluid to the extracorporeal circuit directly. The separate replacementfluid pump can be provided on the PD unit 20 or the HD unit 40. Theseparate replacement fluid is more likely provided with PD unit 20, sothat the replacement fluid supply can be kept with the dialysate supply12 (e.g., either bagged dialysate or on-line dialysate). Any of thepumping technologies described herein for dialysate pump 24 can be usedfor the separate replacement fluid pump.

While the PD/blood systems described herein can be provided with aseparate substitution fluid supply and pump, one alternative apparatusis discussed in connection with FIGS. 6 and 7. FIGS. 6 and 7 illustratea system having the pumping configuration of system 80. It should beappreciated however that any of the pumping technologies of thedifferent PD/blood systems can be used in connection with the teachingsof FIGS. 6 and 7. FIGS. 6 and 7 illustrate a push-pull technique forperforming hemodiafiltration. Here, after using the fresh dialysate toperform pure HD, the PD/blood system uses the eighteen liters ofonce-used dialysate to perform a convective clearance. To do so, theto-and from-dialysate lines 38 a and 38 b, respectively, are opened andclosed selectively to cause dialysate to be pushed either into theextracorporeal circuit or to be pulled from the extracorporeal circuit.The hollow fiber membranes located within dialyzer 42 act as a filter tohelp prevent some of the waste and toxins located within the once-useddialysate from re-entering the extracorporeal circuit. That is, themembranes tend to reclean the spent fluid. Dialysate cleaning cartridge62 may also be used to at least partially clean the once-used, dialysatefor the push-pull convective phase.

In FIG. 6, HD cassette 30 b causes recirculation bag line from-dialysateline 38 b to be closed (as indicated by the X's). Pumps 24 a into 24 bdrive spent dialysate through to-dialyzer line 38 a and into theextracorporeal circuit through the membranes of dialyzer 42. In FIG. 7,the valve state of HD cassette 30 b is reversed, so that source bag 12 a(for example) and to-dialyzer line 38 a are closed (as indicated by theX's), while from-dialyzer line 38 b and a valve enabling dialysate toflow to recirculation bag 18 are opened. Pumps 24 a and 24 b pull spentdialysate from the extracorporeal circuit, through the porous membranesof dialyzer 42, to recirculation bag 18. Over a number of push-pullcycles, more fluid is removed from the extracorporeal circuit than issent into the extracorporeal circuit, resulting in a net fluid removalfrom the patient or ultrafiltrate.

Using the first eighteen liters to perform a diffusive clearance and thesecond eighteen liters to perform a convective clearance makes use ofthe fact that at the end of the diffusive process, the dialysate andblood liquid concentrations tend to be at a equilibrium. That is, theosmotic gradient between the blood liquid and dialysate has beenlessened to the point that dialyzing the patient further at least forcertain toxins may not have much cleansing affect.

Delivering the second eighteen liters to the extracorporeal circuitdirectly makes use of any remaining convective potential in thedialysate. The notion here is that the dialysate after one pass is still“cleaner” than the blood liquid. thus replacing the blood liquid withthe once-used dialysate via, e.g., the push-pull method has a furthercleansing effect.

The dual eighteen liter diffusive than convective treatment has anoverall hemodiafiltration effect because both types clearance modes areused. The method is a-typical however because the different clearancemodes are performed at different times. Typical HDF using an additionalsubstitution fluid-pump enables dialysate to be passed along themembranes of the dialyzer and substitution to be delivered to theextracorporeal circuit at the same time.

FIGS. 8A to 8D illustrate a single needle type push-pull HD/PD system.FIG. 8A shows dialysate pumps 24 a and 24 b generally and a peristalticversion of blood pump 50. It should be appreciated however that any ofthe pumping technologies of the different PD/blood systems can be usedin connection with the teachings of FIGS. 8A to 8D. It is contemplatedto use the push-pull technique for the single needle system incombination with pure HD, pure HF or alone throughout the entire courseof therapy. That is, assuming eighteen liters of bagged solution insupplies 12 a to 12 c is used, the first eighteen liters can be pure HDor pure HF, after which the second eighteen liters is used with thesingle needle push-pull method of FIGS. 8A to 8D. Alternatively, thesingle needle push-pull method can be used throughout the entiretherapy, for example, using it with the fresh eighteen liters only or incombination with a reuse of the eighteen liters.

As with the push-pull system of FIGS. 6 and 7, to- and from-dialyzerlines 38 a and 38 b, respectively, are opened and closed selectively tocause dialysate to be pushed either into the extracorporeal circuit orto be pulled from the extracorporeal circuit. If it is intended to reusethe first eighteen liters of dialysate, dialyzer 42 acts as a filter forthe reused dialysate. Alternatively, cleaning cartridge 62 describedabove is provided to clean the once-used dialysate.

In FIG. 8A, arterial line 52 and venous line 54 tee into a single lumenor needle 53. Single needle 53 is used to allow the system of FIG. 8A topush or pull blood to or from the patient intermittently.

FIG. 8B illustrates a “push” phase of the single needle system of FIG.8A. Here, a valve within PD unit 20 closes or occludes dialysate returnline 38 b or a corresponding path within dialysate cassette 30 b.Dialysate pumps 24 a and 24 b pump dialysate through to-dialyzer line 38a into dialyzer 42. The arrows shown in FIG. 8B within the circuit ofdialyzer 42 indicate that the resulting transmembrane pressure is suchthat dialysate is forced through the membranes of dialyzer 42 and intoarterial and venous lines 52 and 54 of the extracorporeal circuit,resulting in a net flow of blood and dialysate into the patient throughsingle needle access 53.

FIG. 8C illustrates a “hemodialysis” phase of the therapy for the singleneedle system of FIG. 8A. Here, between “push” and “pull” phases, PDunit 20 pumps fresh dialysate to dialyzer 42 through line 38 a andremoves spent dialysate from the dialyzer 42 via return dialysate line38 b. This procedure for example is performed for a long enough time toclean the amount of blood residing within arterial line 52, dialyzer 42and venous line 54. Ultrafiltration or a net removal of liquid can alsobe performed during the hemodialysis phase of FIG. 8C. During thisphase, single access line 53 is occluded as illustrated in FIG. 8C, forexample, via a valve or occluder, such as valve 74 located within bloodunit 40.

Referring now to FIG. 8D, a “pull” phase of the single needle system ofFIG. 8A is illustrated. Here, single needle access 53 is opened,to-dialyzer line 38 a is occluded and PD unit 20 pulls fluid fromdialyzer 42. This sequence causes a transmembrane pressure withindialyzer 42 to conduct fluid from the extracorporeal circuit, throughthe membranes of dialyzer 42, and out from-dialyzer line 38 b asindicated by the arrows of FIG. 8D.

The single needle, push-pull system of FIG. 8A is advantageous in anumber of respects. For one, single needle access is less cumbersome tothe patient. Second, problems due to needle dislodgement are not nearlyas serious as with a dual access system. The most serious accessdisconnection problem occurs when a venous or return needle in a dualaccess system becomes dislodged, while the arterial needle remainslodged. Here, blood pump can continue to pull blood from the patient andreturn the blood outside of the patient. In the single needle system ofFIG. 8A, if a needle dislodgement occurs, the patient potentially losesthe amount of blood existing within dialyzer 42 and arterial and venouslines 52 and 54, but no more.

A further advantage of the single needle system of FIG. 8A is that bloodpump 50 only has to rotate in one direction. In many single needlesystems, two blood pumps are provided. Or, a complex valve and linearrangement is needed for a single blood pump 50 to be used. Here, onthe other hand, arterial and venous lines 52 and 54 can be left open,while blood pump 50 rotates in single direction, simplifying the valvingto occlude access line 53 and the dialysate to-and from-lines 38 a and38 b at the appropriate times.

Referring now to FIGS. 9A and 9B, a continuous or dual, single needlesystem is illustrated in two valve states. As stated above, singleneedle systems are advantageous in one respect due to their inherent andrelative immunity to access disconnection problems. One drawback oftypical single needle systems however is reduced clearances. In essence,single needle systems are less efficient than dual needle systemsbecause single needle systems are either filling or removing fluid to orfrom the patient at any given time. Dual needle systems perform bothfunctions simultaneously, increasing clearance efficiency.

The system of FIGS. 9A and 9B performs two single needle therapiessimultaneously, increasing the overall efficiency of the system. In oneembodiment, one single needle fills the patient while the other singleneedle removes fluid from the patient, and vice versa, creating avirtually continuous flow. Pushing and pulling through each needleeliminates the dedicated “venous” needle found with circulatory dualneedle systems and thus eliminates the most dangerous accessdisconnection element. Providing two single needle therapies howeverallows more fluid to be delivered to and removed from the patient for agiven period of time versus standard single needle systems.

It is contemplated to use the dual, single needle system in combinationwith pure HD, pure HF or alone throughout the entire course of therapy.That is, assuming eighteen liters of bagged solution in supplies 12 a to12 c is used, the first eighteen liters can be pure HD or pure HF, afterwhich the second eighteen liters is used with the dual, single needlesystem and method of FIGS. 9A and 9B. Alternatively, the dual, singleneedle system and method can be used throughout the entire therapy, forexample, using it with the fresh eighteen liters only or in combinationwith a reuse of the eighteen liters.

For convenience, dialysate pumps 24 a and 24 b of the dual-single needlesystem of FIGS. 9A and 9B are not illustrated but connect to dialyzer 42via to- and from-dialyzer lines 38 a and 38 b as has been describedherein. A peristaltic version of blood pump 50 is illustrated, however,it should be appreciated that any of the pumping technologies of thedifferent PD/blood systems described herein can be used in connectionwith the teachings of FIGS. 9A to 9B.

Unlike the push-pull system of FIGS. 8A to 8D, to- and from-dialyzerlines 38 a and 38 b, respectively, do not have to be opened and closedselectively to cause dialysate to be pushed either into theextracorporeal circuit or to be pulled from the extracorporeal circuit.Here instead, fresh dialysate is fed continuously (or semi-continuously)to dialyzer 42 via to-dialyzer line 38 a. Spent dialysate andultrafiltrate is pulled continuously (or semi-continuously) fromdialyzer 42 via from-dialyzer line 38 b. The dual, single needleswitching is performed via two three-way 108 a and 108 b that can beactuated electrically, pneumatically or mechanically.

In the illustrated embodiment, single lumen or needle 53 a and 53 bprovide both arterial and venous access to patient 14. Single lumen orneedle 53 a connects to arterial and venous access line 153 a. Singlelumen or needle 53 b connects to arterial and venous access line 153 b.Access lines 153 a and 153 b each connect fluidly to both three-wayvalves 108 a and 108 b. Valve 108 a is the valve through which all fluidremoved (through either line 153 a or 153 b) from the patient (arterialfluid) flows. Valve 108 b is the valve through which all fluid delivered(through either line 153 a or 153 b) to the patient (venous fluid)flows. Accordingly, all fluid flowing through valve 108 b must flowthrough drip chamber 82 (and any other desirable apparatus disclosed forexample in connection with FIGS. 10 and 11) and blood return line 48.

In the extracorporeal circuit of FIGS. 9A and 9B, blood pump 50 pullsfluid from patient 14, through three-way valve 108 a and pushes bloodthrough dialyzer 42, drip chamber 82 and three-way valve 108 b back topatient 14. Three-way valves 108 a and 108 b are reversed insynchronization in one embodiment such that: (i) pump 50 pulls fluidfrom patient 14, though single access needle 53 b , line 153 b and valve108a, while pumping fluid through drip chamber 82, valve 108 b, line 153a and single access needle 53 a to patient 14 (FIG. 9A, in which openedvalves are darkened); after which valves 108 a and 108 b switch statesso (ii) pump 50 pulls fluid from patient 14, though single access needle53 a , line 153 a and valve 108 a, while pumping fluid through dripchamber 82, valve 108 b, line 153 b and single access needle 53 b topatient 14 (FIG. 9B, in which opened valves are darkened).

The embodiment illustrated in FIGS. 9A and 9B is most likely used forconventional HD, HF or HDF and not push/pull variations of thosetherapies, since it may be difficult to combine the push-pull switchingin the dialysate circuit (e.g., FIGS. 8A to 8D) with the switching ofblood valves 108 a and 108 b. The embodiment illustrated in FIGS. 9A and9B can also be used with conventional hemodialysis machines as a way toaddress assess disconnect issues. It should be appreciated that thefluid through blood return line 48 b can come from dialyzer 42 (HD), asource of replacement fluid (HF) or both (HDF). Further alternatively,the dual dialyzers 42 a and 42 b and backpressure restriction 56 ofFIGS. 10 and 11 can be used in place of dialyzer 42 in the system ofFIGS. 9A and 9B.

Referring now to FIGS. 10 and 11, two systems 110 and 120 for performinga simultaneous diffusion/convection therapy are illustrated,respectively. Systems 110 and 120, like the push-pull method, areadvantageous because a separate substitution supply is not needed.Systems 110 and 120 are described in detail in U.S. patent applicationSer. No. 10/982,170, entitled: “High Convection HomeHemodialysis/Hemofiltration And Sorbent System”, filed Nov. 4, 2004,assigned to the assignee of the present application, the entire contentsof which are incorporated herein by reference.

Systems 110 and 120 have separate or combined PD and HD units 20 and 40as described above (shown separately here). System 110 employs two ormore high flux hemodialyzers, such as a venous dialyzer 42 a and anarterial dialyzer 42 b. In one embodiment, hemodialyzers 42 a and 42 bare relatively small, e.g., on the order of one quarter meter to threemeters of membrane surface area. Dialyzers 42 a and 42 b are relativelyhigh flux dialyzers, e.g., having a UF coefficient of eight millilitersof water diffused per hour per millimeters Hg pressure or greater (asused herein, the term “flux” refers to the above UF coefficient, whichmeasures the ease of water transport through the membrane, expressed inmilliliters/hour/millimeter Hg.

Variable restriction 56 placed between dialyzers 42 a and 42 b causebackfiltration in the venous dialyzer 42 a of a relatively large portionof the fresh dialysate. The backfiltered dialysate and the fluidaccumulated during the interdialytic period is ultrafiltered or removedfrom the patient 42 via the arterial dialyzer 42 b. The fluid notbackfiltered flows across the semi-permeable membranes in the arterialand venous dialyzers, enabling system 110 to provide both diffusive andconvective removal of waste from the patient's blood.

As above, sterile dialysate is stored in bags or containers 12 a to 12 c(more than three solution bags may be used). System 110 employsvolumetric dialysate pumps 24 a to 24 d that each operate with aflexible membrane 72 as described above to pump dialysate accurately.Here, flowrate and volume pumped are calculated based on a summation ofpump chamber volumes per unit time or over time for dialysate pumps 24 ato 24 d.

System 110 of FIG. 10 illustrates two pumps 24 a and 24 b for a Pump Set1 and two pumps 24 c and 24 d for a Pump Set 2. Alternatively, a singlepump is used in place of each set of pumps, e.g., one to input dialysateto the dialyzers 42 a and 42 b and one to remove dialysate from thedialyzers and UF from the patient. That configuration however createspulsatile or uneven flow, which may be less desirable. In theillustrated configuration, a first pump of each set is pulling fluidfrom the pump set's source, while a second pump of each set is pushingfluid towards the pump set's destination. After that set of pumpstrokes, the roles of the pumps in the respective sets alternate, sothat the first pump (now full of fluid) pushes fluid towards the pumpset's destination, while the second pump (now empty) pulls fluid fromthe pump set's source. The above cycle is repeated multiple times.

Pump Set 1 inputs fresh dialysate from bags 12 a to 12 c to dialyzers 42a and 42 b of system 110 and Pump Set 2 removes a volumetric equivalentof the fluid pumped by Pump Set 1 and any extra fluid removed frompatient 14 (“UF”) during the course of the treatment. As illustrated,fresh dialysate is pumped via pumps 24 a and 24 b from sources 12 a to12 c through to-dialyzer line 38 a to the venous dialyzer 42 a. Arestriction 56 is located between venous dialyzer 42 a and arterialdialyzer 42 b. Restriction 56 builds pressure in venous dialyzer 42 a,so that a relatively large amount of fresh dialysate entering venousdialyzer 42 a is forced through the walls of the membranes inside venousdialyzer 42 a and into the extracorporeal or blood circuit 102. Theother portion of the fresh dialysate entering venous dialyzer 42 a flowsacross the membranes inside venous dialyzer 42 a, through restriction 56and into arterial dialyzer 42 b. Restriction 56 can be variedautomatically to control back filtration.

Convective clearance occurs when a volumetric equivalent of the fluidbackfiltered through venous dialyzer 42 a is removed through return line38 b from the arterial dialyzer 42 b. Also, a diffusive transport oftoxins occurs across both dialyzers 42 a and 42 b due to a diffusivegradient that exists between blood within the dialyzers and blood path102 and the dialysate flowing through the dialyzers. Over the totaltherapy, the total amount of fluid removed from the arterial dialyzer 42b is greater than the total amount of dialysate supplied to the venousdialyzer 42 a, accounting for an amount of UF removal prescribed for thetherapy.

In one example, pumps 24 a and 24 b of Pump Set 1 infuse eighteen litersof dialysate from sources 12 a to 12 c over two hours. Of that volume,one hundred ml/min of dialysate is backfiltered into the blood circuit102 through the membrane walls of venous dialyzer 42 a. Fifty ml/min ofdialysate passes through the venous dialyzer 42 a, restriction 56, andinto venous dialyzer 42 b. Pumps 24 c and 24 d of Pump Set 2 remove thetotal of eighteen liters of dialysate from dialyzer 42 b and back intodrain or bags 16, 18 and potentially 12 a to 12 c plus any desiredamount of fluid from the patient. Over the example two hours, twelveliters (100 ml/min multiplied by 120 minutes) of dialysate isbackfiltered into the patient's blood through the venous dialyzer 42 a.Pumps 24 c and 24 d of Pump Set 2 remove that twelve liters, the sixliters of dialysate that is not backfiltered into blood circuit 102 plusany fluid ultrafiltered from the patient.

The addition and removal of the twelve liters of dialysate from bloodcircuit 102 over the two hour therapy yields an overall convectiveremoval according to the equation HF stdKt/V of ˜2, which has beenreported to be a suitable daily amount (see Jaber B T, Zimmerman D L,Leypoldt J K Adequacy of Daily Hemofiltration: Clinical Evaluation ofStandard Kt/V (stdKt/V), Abstract Hemodialysis International Volume 7,number 1, p 80, 2003. Additionally, over the course of the example twohours, six liters of dialysate is used for diffusive clearance via thedialysate gradient across the membranes of dialyzers 42 a and 42 b. Thedialysate flowrates and percent convective versus diffusive could behigher or lower than those used in the example.

Dialyzers 42 a and 42 b and flow restriction 56 may be attached toeither HDF dialysate cassette 30 b or blood cassette 44. Blood cassette44 as seen includes at least a portion of the extracorporeal circuit102. For example, in system 110 all of extracorporeal circuit 102 isintegrated into cassette 44 with the exception of the arterial andvenous tubing 52 and 54 going to and from the patient. HHD dialysatecassette 30 b in turn provides a space efficient apparatus for handlingthe dialysate or therapy fluid flow portions of the pumps 24 a to 24 dand valves 86 described herein, which are actuated pneumatically ormechanically as desired. Cassettes 30 b and 44 are well suited for homeuse, where space, capability and resources are limited.

In one preferred embodiment, HDF dialysate cassette 30 b and bloodcassette 44 and any associated attached tubing are gamma sterilized andsealed prior to use. Alternatively, sterilization via ethylene oxide orE-Beam is employed. The patient or operator opens a sealed wrapper justprior to use, inserts cassettes 30 b and 44 (or single cassette forboth) into PD and HD units 20 and 40, respectively (or single combinedunit) for a single use and then discards the cassettes and associatedtubing after use. While blood cassette 44 and HDF cassette 30 b andrespective flow paths 102 and 104 are intended for a single use in oneembodiment, they could be reused with suitable disinfection and/orsterilization.

As seen in FIG. 10, beginning from the arterial access 52 of the patient14, the extracorporeal or blood circuit 102 includes a pressure sensor78, labeled PT1. PT1 is alternatively a pressure switch with the abilityto stop blood flow prior to reaching blood pump 50. As a safety measure,system 110 in one embodiment includes a multitude of electrodes (shownin FIG. 11), such as two to four electrodes, which provide electricalcontacts for an access disconnection sensor described for example incopending patent application entitled, “Conductive Polymer Materials AndApplications Thereof Including Monitoring And Providing EffectiveTherapy”, Ser. No. 10/760,849, filed Jan. 19, 2004, assigned to theassignee of the present disclosure, the entire contents of which areincorporated herein by reference. An alternative mechanism for detectionof accidental needle disconnections is the use of a conductive blanketunderneath the patient access. The presence of blood changes theconductivity of the blanket, causing an alarm and a stoppage of thepumps.

Blood pump 50 is a peristaltic pump in the illustrated embodiment and islocated between pressure sensor PT1 and a drip chamber 82 a, which hasan integral pressure transducer 78, labeled PT2. The drip chambers 82 ato 82 c remove air from fluid passing through the drip chambers. One, amultiple of or all the drip chambers 82 a to 82 c in an alternativeembodiment includes an associated level sensor 98. Sensors 98 areconnected to or integrated into the associated drip chambers. Levelsensors 98 sense and indicate the level or height of dialysate ortherapy fluid in the. Each drip chamber 82 a to 82 c can also include avent 44 and associated valve 86.

As discussed above in connection with FIG. 3, blood pump 50 isalternatively a volumetric pumping device (or otherwise the same type ofpump as dialysate pumps 24 a and 24 b). Blood pump 50 can also bebidirectional for system priming and rinseback as discussed herein.Pressure sensor PT2 78 is alternatively not associated with a dripchamber, for example in a case in which pressure transducers associatedwith blood circuit 102 are used instead. Arterial and venous lines 52and 54, pressure sensors PT1 and PT2, drip chambers 82 a to 82 c as wellas the pathways for much of blood circuit 102 and tubing for peristalticpump 50 are provided by or connected to blood cassette 44 in oneembodiment.

After drip chamber 82 a, blood flows out of cassette 44 and into arelatively small, high flux arterial dialyzer 42 b. Arterial dialyzer 42b and venous dialyzer 42 a are attached in one embodiment to a housingof blood cassette 44. In an alternative embodiment, the dialyzers areconnected to HDF dialysate cassette 30 b (or a single cassette for bothblood and dialysate). Blood then flows from the arterial dialyzer 42 bto the venous dialyzer 42 a, back into blood cassette 44 and through asecond drip chamber 82 b. Drip chamber 82 b also has an integralpressure sensor 78, labeled PT3. PT3 is alternatively provided without adrip chamber when, for example, pressure transducers coupled directly toblood circuit 102.

An air bubble detector 84 labeled ABD is located downstream from dripchamber 82 b in blood circuit 102. A venous line clamp or valve 86,labeled V1, which may be cassette-based or provided externally to bloodcassette 44, and which shuts down blood flow if detector 84 detects airin blood circuit 102, is located between the air detector 84 andarterial access 54, which returns cleansed blood to patient 14. An airlevel sensor (not illustrated) on drip chamber 82 b is usedalternatively or in addition to ABD 84.

To detect air in the blood, a level detect scheme is alternatively oradditionally provided with drip chamber 82 b or pressure transmitter 78,labeled PT3. For example, an ultrasonic sensor can be placed on oppositesides of the drip chamber. The ultrasonic sensor generates a signal thatdepends upon the percentage of air in the blood passing betweentransmitting and receiving portions of the sensor. Under normaloperation, when no air is present, the blood within drip chamber 82 bresides at a relatively steady level, although level fluctuations dooccur due to changes in pressure, amount of blood pumped, etc. Athreshold level of blood in chamber 82 b does exist below which theblood should not drop. When air in the blood lines is present, the bloodlevel in the chamber 82 b is lower than threshold level, triggering analarm from the alternative air/blood detector. It is important to notethat an air detector and line clamp may be used additionally on thearterial side of blood circuit 102, if required for rinse, prime orblood rinseback, for example.

The dialysate flow path is also located primarily in HDF cassette 30 b(or in a combined blood and dialysate cassette). The dialysate issupplied from dialysate supply bags 12 a to 12 c. In alternativeembodiments (applicable to each of systems 10, 70, 80, 90, 100, 110 and120), the dialysate source can be an on-line source or other type ofnon-prepackaged source. In systems 10, 70, 80, 90, 100, 110 and 120, aminimum of one infusion bag is provided, and in one preferred embodimentmultiple bags, such as three sources 12 a to 12 c are provided. Asdiscussed above, system 110 can also be provided with an empty drain orrecirculation bag 18, which is filled with spent solution from thesupply bag that is used first, and so on. Because the therapy in the endremoves more fluid than is inputted, each of the supply bags 12 a to 12c and recirculation bag is used to receive spent fluid and UF. The bagsequencing is controlled as illustrated by valves 86 , labeled V2 to V8.

Dialysate flows from one of sources 12 a to 12 c to the volumetricdiaphragm pumps 24 a and 24 b of Set 1. The volumetric accuracy of pumpsis confirmed by monitoring. As discussed above, it is desirable to usetwo alternating solution delivery pumps 24 a and 24 b to limit theamount of pulsitile flow. As a safety measure, the diaphragms of each ofthe pumps 24 a to 24 d are configured so that if they leak, they canonly leak externally. Any leaks collected externally from pumps 24 a to24 d are then diverted towards a moisture sensor built into the cassette30 b, machine and/or cassette/machine interface, which senses such leakand signals: (i) an alarm; (ii) to shut down pumps 24 a to 24 d and 50;and (iii) to take any other appropriate action.

Referring now to FIG. 11, HDF system 120 employing balancing chambers(discussed in connection with FIG. 4) is illustrated. System 120includes many of the same components described above, which are shownwith like numbers that do not need to be re-described. Further, system120 is shown in operation with the enhanced convection hemodialysis(“ECHD”) dual high flux dialyzers 42 a and 42 b and variable restriction56. It should be apparent however from the previous descriptions thatsystem 120 can operate with any of the modalities described herein.

System 120 includes HD unit 40 and PD unit 20. In the illustratedembodiment, HD unit 40 operates with a blood cassette 44, which includesportions for valves 86, such as venous line 54 valve V1, drip chambers82 b and 82 c (including pressure sensors 78 and vents 94). Tubing forblood pump 50 is also connected to blood cassette 44 in one embodimentas is tubing connected to the blood connectors of dialyzers 42 a and 42b. Blood cassette 44 is also connected to a portion of arterial line 52and venous line 54. Cassette 44 also defines valved blood flow pathwaysin fluid communication with the external tubing mentioned above.

HD unit 40 in one embodiment provides access disconnection points 140 aand 140 b, which sense and cause an alarm if an electrical conditionchanges due to an access disconnection of either arterial line 52 orvenous line 54 from patient 14. HD unit 40 in the illustrated embodimentalso houses or holds dialyzers 42 a and 42 b and flow restriction 56. Inan alternative embodiment, PD unit 20 houses or holds those items. In afurther alternative embodiment, HD unit 40 and PD unit 20 are combinedinto a single unit, which houses or holds those items.

In the illustrated embodiment, PD unit 20 operates with an HDF dialysatecassette 30 b, which includes all or portions of fresh solution inletpathways 122 a and 122 b (extending from supply line 32), spent solutioninlet pathways 124 a and 124 b (extending from from-dialyzer line 38 b),fresh solution outlet pathways 126 a and 126 b (feeding into to-dialyzerline 38 a), and spent solution outlet pathways 126 a and 126 b (feedinginto drain line 36). Pathways 122 a and 126 a communicate fluidly with afresh compartment 130 a of balance chamber 92. Pathways 124 a and 128 acommunicate fluidly with a spent compartment 132 a of balance chamber92. Fresh compartment 130 a and spent compartment 132 a are separated bya flexible membrane 72 discussed above. Pathways 122 b and 126 bcommunicate fluidly with a fresh compartment 130 b of balance chamber94. Pathways 124 b and 128 b communicate fluidly with a spentcompartment 132 b of balance chamber 94. Fresh compartment 130 b andspent compartment 132 b are also separated by a flexible membrane 72.

In an embodiment, HDF dialysate cassette 30 b supplies the fluidcarrying portion of balance chambers 92 and 94. Balance chambers 92 and94 may be referred to herein collectively as a flow equalizer. Suitableembodiments for incorporating balance chambers 92 and 94 into a cassettesuch, as HDF dialysate cassette 30 b are disclosed in copending patentapplication referenced above. PD unit 20 provides rigid chambers intowhich the flexible components of balance chambers 92 and 94 of cassette30 b are positioned. PD unit 20 also provides pneumatic actuation in oneembodiment to pull the outer sheets of balance chambers 92 and 94 apartso that inner flexible membranes 72 can be flexed back and forth byincoming fresh/spent and outgoing spent/fresh fluids, respectively.

In a first exchange cycle, one of the balance chambers 92 or 94 fillswith fresh solution and at the same time delivers an equal volume ofspent dialysate to drain. In that same first cycle, the other balancechamber 92 or 94 fills with effluent dialysate and at the same timepushes a like volume of fresh dialysate to dialyzers 42 a and 42 b orthe patient according to the modality. Then, in a second cycle, thebalance chambers 92 and 94 alternate functions so that the balancechamber that previously delivered fresh dialysate to the patient nowdelivers spent dialysate to drain, while the balance chamber thatpreviously delivered spent dialysate to drain now delivers freshdialysate to the dialyzer or patient. There is a short dwell time at theend of each exchange cycle when all valves are closed. The valves can bechecked for leaks at this time.

In one embodiment (not illustrated), system 120 dedicates the flowequalizer or dual balance chambers 92 and 94 to removing an amount offluid from the dialyzer, while at the same time filling the dialyzerwith a like amount of fluid. Here, a separate UF pump or UF meter isused to remove a known amount of UF. In the illustrated embodiment,however, system 120 uses the flow equalizer or balance chambers 92 and94 for UF removal as well as for balancing flow to and from dialyzers 42a and 42 b. The valve operation for removing a net loss orultrafiltration of fluid from the patient includes opening valves V1,V2, V6, V7, and V9, while closing valves V3, V4, V5, V8 and V10. Thisvalve configuration pushes effluent dialysate to drain by pushing thefresh dialysate from balance chamber 94 to balance chamber 92.

System 120 enables an ultrafiltrate removal rate to vary over time,which is sometimes referred to as an ultrafiltrate profile. For example,if an ultrafiltrate cycle is performed on average after five exchangecycles to remove a desired amount of UF over the course of treatment,one could change the frequency at which ultrafiltrate is removed fromthe patient by increasing or decreasing the frequency of cycles duringdifferent times of treatment, but which average out to one UF stroke toevery five exchange strokes. This could result, for example, in morefluid being removed during a first part of therapy than a second. Theprocessor of control unit 26 is configured to run an algorithm, whichenables the patient to select a profile, a treatment time and an overallvolume to be removed. The algorithm automatically calculates anultrafiltrate rate profile that achieves, according to the profile, anentered net cumulative ultrafiltrate volume over an entered treatmenttime. Those parameters may be entered alternatively through a patientdata card or through a secure data connection.

In the illustrated embodiment, dialysate pumps 24 a and 24 b areperistaltic pumps. They may alternatively be membrane pumps or othertypes of pumps described herein. Tubes for dialysate pumps 24 a and 24 bin an embodiment are connected fluidly to appropriate valved pathways ofHDF cassette 30 b. Fresh dialysate pump 24 a is shown upstream of heater58. Alternatively, heater 58 is located upstream of pump 24 a. Heater 58can be of any suitable type, such as resistive, convective, radiant, andany combination thereof. Heater 58 is shown as being an in-line fluidheater. Heater 58 for any of the systems described herein can be inlineor of a batch type, such as with the HomeChoice® APD system.

System 120 can also provide a bolus of solution to the patient whenneeded. Valves V2, V3, V7, V8 and V10 are opened and valves V1, V4, V5,V6 and V9 are closed. Pump 24 a is run forcing one balance chamber bolusof dialysate and/or substitution fluid to the dialyzer or patient.

In any of the embodiments described herein, it is important that valves86 of the systems are checked to ensure that they open and closeproperly. In one embodiment, the valves are checked periodicallythroughout treatment using conductive sensing. That is, if fluid escapesfrom the system via a faulty valve or tear in a cassette membrane,conductive sensors that measure a flow of electricity across a liquidcan send an alarm and trigger appropriate action. Further, withcassettes 30 b and 44, temperature sensing may be employed, for example,by applying a thermistor, IR sensor or thermocouple on one side of thesheeting of the cassette. Here, the temperature sensors are attached toPD and HD units 20 and 40 and, for example, contact the sheetingmembrane so as to obtain a quick reading of the temperature of thedialysate or blood.

The above described systems show multiple embodiments for performing acombination therapy including any one or more of peritoneal dialysis,hemodialysis, hemofiltration and hemodiafiltration. The embodiments alsoshow different pumping technologies that can be used for any of these.The embodiments enable a dialysis patient to alternate from PD to HD inthe same week or even the same day if desired. The tradeoff is that apatient is willing to accept and perform a dual access, namely, one forPD and one for HD.

The hybrid therapy allows the patient to take advantage of beneficialcharacteristics for each of PD and blood treatment such as HD, HF andHDF, while minimizing less desirable traits of each. For example, withPD, an osmotic agent, e.g., glucose, is needed to perform UF. Theosmotic agent is believed to cause gradual (diffusive) deterioration ofthe peritoneal lining. HD on the other hand can accurately achieve UFwithout use of an osmotic agent. HD extracts UF directly from the blood.With HD however blood is pulled from the body and is exposed to innerand foreign surfaces and pressure involved with the pumping of theblood. In many cases, HD therapy requires the addition of anticollagens,such as hyperion, into the blood to keep blood from congealing withinarterial line 52, venous line 54 and dialyzer 42.

The above described systems enable the patient to take advantage of HD'sability to control UF without an osmotic agent and PD's ability toremove solutes without removing blood from the patient. Here, it iscontemplated to perform PD using a psychologically stable solution inthe absence of an osmotic agent. Accordingly, the gradual detrimentaleffects due to PD would not occur. This would allow PD patients toremain on PD for a longer period of time. The PD solution would takeadvantage of the concentration ingredient of solute, e.g., creatinine,urea, uric acid, etc. In essence, PD is used to perform necessaryclearance of impurity that build up within the patient due to thepatient's kidney failure. HD or one of the blood treatments are thenperformed to provide the necessary ultrafiltration. In this manner, theblood treatment can be performed as quickly and safely as possiblebecause its primary purpose is to remove UF. In this manner, the amountof time the patient spends performing HD could be minimized, therebyminimizing the amount of time that blood is external to the patient'sbody.

As described herein, in one preferred embodiment, HD unit 40 is providedseparately from PD unit 20. In this manner it is contemplated to providea PD unit 20 that stands alone to perform peritoneal dialysis. If it isdesired to perform a blood treatment additionally or alternatively tothe PD therapy, then the HD unit 40 can be added. Providing separateunits creates various issues related to electromechanical architecture,which are now addressed.

Control Architecture

Referring now to FIGS. 12A to 12G, various system architectures for thesystems described herein are illustrated. FIG. 12A illustrates variousexternal factors or logistics affecting the PD/HD control architecturedescribed below. The systems described herein are configurable to beused at home, in which case the user of the system can be the same asthe patient. Alternatively, the systems described herein areconfigurable to be used in a center or at home, but wherein the systemis operated by someone other than the patient, e.g., a clinician, nurse,doctor or family member. The systems typically have to accommodatedialysate supply bags and other supply bags for HD (or other type ofblood therapy described herein), such as heparin (or otheranticoagulant) and saline (for priming and blood rinseback). It is alsocontemplated that the systems in an HD or HDF mode use dialysate madeonline instead of bagged dialysate. The systems also have to accommodateboth PD and HD disposable sets including the relevant disposablecassette and associated tubing. HD can use separate dialysate and bloodcassettes or a single cassette for both the flow of dialysate and blood.

FIG. 12B illustrates one embodiment of a disposables architecture forthe HD and PD units 40 and 20 in connection with the various systemsdescribed herein. Each unit includes its own disposable set including anassociated disposable cassette and associated tubing. For example, PDunit 20 operates a dialysate cassette 30, which can be configured for PDas cassette 30 a or for HD as cassette 30 b as described in detailherein.

When PD is performed, tubing associated with dialysate cassette 30aincludes patient line 34, one or more supply line 32 and drain line 36(see, e.g., FIG. 1). Depending on the type of dialysate heatingemployed, the associated tubing can also include a to-and from-heaterline.

When HD is performed, tubing associated with dialysate cassette 30bincludes to- and from-dialyzer lines 38 a and 38 b, one or more supplyline 32 and drain line 36 (see, e.g., FIG. 1). Again, depending on thetype of dialysate heating employed, the associated tubing can alsoinclude a to- and from-heater line. Further, when HD is performed aseparate (or integrated) blood cassette 44 is also provided as shown indetail below. Tubing associated with blood cassette 44 includes arterialand venous lines 52 and 54, dialyzer blood lines 48 a and 48 b and primeand rinseback line 28.

FIG. 12C schematically illustrates various embodiments for a powersupply architecture for PD unit 20 and HD unit 40. In FIG. 12C, eachunit or system 20 and 40 includes a separate supply of power 112, e.g.,an alternating current supply. It should be appreciated however that thepower supply 112 is alternatively a direct current power supply. Furtheralternatively, universal power supplies 112 can be formatted foroperating with 120 VAC or 240 VAC mains voltage as needed. In oneembodiment, power supplies 112 are identical for both PD units 20 and HDunit 40.

AC power 112 feeds a power supply unit 114, which in one embodiment isthe same for both PD unit 20 and HD unit 40. In an embodiment, powersupply unit 114 converts the input voltage 112 to a desired type andlevel. The dual power supply arrangement alleviates problems due toelectromagnetic interference (“EMI”), electromagnetic compatibility(“EMC”) and electrostatic discharge (“ESD”), which could otherwise occurby using the same power unit 114 for both PD unit 20 and HD unit 40.Using the same power supply 114, one each for PD and HD units 20 and 40,simplifies design and manufacturing costs.

It is also contemplated however to use a single AC power supply 112 andpower supply unit 114 if it is believed that conductive path problemswill be minimal or can be minimized The single supply configurationreduces hardware and potentially software otherwise associated with twoseparate power supplies.

As discussed above, in one embodiment HD unit 40 and PD unit 20communicate via a non-electrical or wireless mode 60 of transmission.This also alleviates problems due to EMI, EMC and ESD, which can createproblems at the design level because of possible conduction paths that ahard-wired linking of PD unit 20 and HD unit 40 can create. The wirelesscommunication 60 can be of any suitable type, such as RF, encoded RF,secured Bluetooth, microwave, infrared or others.

In the illustrated embodiment, PD unit 20 is linked electromechanicallywith a graphical user interface (“GUI”) 116. It should be appreciatedhowever that HD unit 40 can also be connected to a separate GUI 116. Inone embodiment, GUI 116 enters and provides information for any of thetreatments discussed herein including PD and/or blood treatments. Inthis manner, the user does not have to learn or become familiar with anew interface when adding a blood therapy to PD unit 20. To this end, inone embodiment software within PD unit 20 looks for a connection viadata link 60 to HD unit 40. Upon sensing the presence of HD unit 40,data link 60 triggers additional and/or different software, so that PDunit 20 enables the HD functions of GUI 116. Allowing the PD module tobe the primary module in the PD unit 20/HD unit 40 combination alsoreduces the amount of mechanical integration needed.

GUI 116 in an embodiment operates with a touch screen, membraneswitches, dials, other mechanical switches and any combination thereof.GUI 116 can also be foldable so that the screen collapses into themachine for protection during travel or when not in use.

FIG. 12D illustrates different software modules that can run aninterchangeable PD or HD therapy. When PD treatment is used, only thesoftware associated with PD unit 20 is needed. When HD is performed,software modules for both PD unit 20 and HD unit 40 are used. PDsoftware includes a treatment management module FM 1.1 PD, whichincludes software configured to control the overall dialysate treatment,e.g., dialysate temperature control, air handling, patient alarms,safety control, etc. For example, treatment management module FM 1.1 PDcan run a part or all of the dialysate portions of the routines shownbelow in connection with FIGS. 19 to 22.

Module FM 1.2 PD includes software configured to control parametersrelated to dialysate pumping, such as, dialysate pumping speed,ultrafiltration control, dialysate line priming, dialysate lineocclusion correction, etc. Module FM 1.2 PD can interface with othermodules, for example, sensing module FM 1.6 PD to receive flowratefeedback for example to maintain one or more dialysate pump at a desiredspeed. In another example, pumping module FM 1.2 PD interfaces withsensing module FM 1.6 PD, such that when the sensing module detects airin the system, the pumping module stops pumping dialysate to the patientor dialyzer or shunts the air laden dialysate to drain. In anotherexample, pumping module FM 1.2 PD interfaces with sensing module FM 1.6PD to run an occlusion correction routine when the sensing moduledetects a low or occluded flow or overpressure condition.

PD dialysis pumping module FM 1.2 PD also interfaces with treatmentmanagement module FM 1.1 PD, which in a pure PD mode tells the dialysatepumping module when the dialysate pump(s) should be pumping dialysisfluid to the patient, be in a dwell state, or to pump effluent or spentdialysate from the patient to drain. PD mode pumping also includes PDpriming, line occlusion correction, air correction, etc.

When in HD dialysis mode, treatment management module FM 1.1 PD can forexample tell pumping module FM 1.2 PD when it is proper to beginpumping. Also, HD dialysate will be pumped typically at a higherpressure than for PD. The dialysate pumping is adjusted accordingly forHD. Further, it is known to run ultrafiltration profiles for HD. Theultrafiltration profiles can be stored for example on treatmentmanagement module FM 1.1 PD, which then interfaces with pumping moduleFM 1.2 PD to tell the pumping module how much ultrafiltration to removeat a given point during therapy. The modules can interface in a similarmanner for sodium profiling.

Module FM 1.3 PD includes software configured to control parametersrelated to docking, e.g., when HD unit 40 is docked to PD unit 20 viadata link 60 as described above in connection with FIG. 12C. In oneembodiment, the architecture is set at a default to run a pure PDtreatment. That is, the system is caused to run software that looks fora PD dialysate cassette 30 a, runs PD dialysate pumping routine and doesnot look for blood cassette 44 or to run a blood pumping routine.

When a separate HD unit is docked to the PD unit (see e.g., FIG. 13B forintegrated HD unit 40, here docking software is triggered when HDcassette 44 is installed; see alternatively FIGS. 18C to 18E whenseparate HD unit 40 is docked to PD unit 20), docking module FM 1.3 PDsenses the additional HD hardware and causes PD unit 20 to run a HDtherapy instead of a PD therapy. That is, the system is caused to runsoftware that looks for an HD dialysate cassette 30 b, runs an HDdialysate pumping routine and also looks for blood cassette 44 and runsa blood pumping routine.

Module FM 1.4 PD includes software configured to control parametersrelated to powering PD unit 20. Particulars for powering PD unit 20 arediscussed above in connection with FIG. 12C.

Module FM 1.5 PD includes software configured to control parametersrelated to the loading of the disposable for PD unit 20. As discussedabove, the system is set in one embodiment at a default to look for PDcassette 30 a and associated tubing. If HD unit 40 is docked, module FM1.5 PD instead runs software for HD cassette 30 b and associated tubing.Module FM 2.5 HD runs software for controlling HD cassette 44 asdiscussed below. Alternatively, the HD cassette software can be locatedat module FM 1.5 PD as discussed in connection with FIG. 12E.

Module FM 1.6 PD includes software configured to control parametersrelated to sensing for PD unit 20. Sensing PD dialysis parametersincludes, for example, sensing PD dialysate pump speed and pressure, PDdialysate temperature, air sensing, conductivity sensing, volumetricsensing (e.g., for total fluid flow and ultrafiltration), etc. Asdiscussed above, the system is preset to sense PD parameters, e.g.,enable readings from PD sensors and use parameter setpoints associatedwith a PD treatment. If HD unit 40 is docked, module FM 1.6 PD insteadruns software for HD dialysis sensing. Many of the same parameterslisted above for PD dialysate sensing are also sensed for the HDtherapy. One difference with HD versus PD is that HD looks for a leakingdialyzer by checking dialysate return line 38 b for the presence ofblood. Another difference for HD dialysate sensing is the monitoring ofsodium level in the dialysate. Module FM 2.6 HD runs software forsensing parameters relating to blood pumping as discussed below.Alternatively, the HD blood flow software can be located at module FM1.6 PD.

Module FM 1.6 PD interfaces with other modules (as do many of thedialysate modules), such as treatment management module FM 1.1 PD and PDdialysis pumping module FM 1.2 PD. The interfacing of different modulesis performed for example via a central processing unit (“CPU”) or otherone or more supervisory processor located on PD unit 20. The CPU forexample runs treatment management module FM 1.1 PD.

Caseworks module FM 1.7 PD refers to the frame or enclosure of the PDunit 20. The enclosure can include lights or other electrical devicesmounted to the enclosure, which require electrical power. Caseworksmodule FM 1.7 PD also includes electrical insulation and radiationshielding associated with PD unit 20.

GUI module FM 3.1 GUI resides on PD unit 20 and in one embodimentcontrols GUI 116 for both PD and HD treatments as described above inconnection with FIG. 12C. Module FM 3.1 GUI includes a video card and asound card if necessary to display information and graphics and toprovide audio instructions or alarms if desired. It is also contemplatedto have module FM 3.1 GUI run patient voice guidance software to receivecertain information from the patient via voice command.

Module FM 3.2 PD includes software configured to control parametersrelated to logging onto and interfacing with PD unit 20, e.g., via acomputer directly, via a wireless network connection, or via a wireddata network, such as an Ethernet, intranet or internet. Module FM 3.2PD can be used by a hospital or clinician for diagnostic purposes, tomonitor treatment effectiveness, to set parameters, etc. For example,certain parameters can be set in the routines of FIGS. 19 to 22 viamodule FM 3.2 PD. Module FM 3.2 PD is configured to enter data andprovide data concerning PD and HD treatments.

FIG. 12D also illustrates software modules that run the blood pumping ofHD unit 40. The HD modules can be located physically on PD unit 20, forexample, if HD unit 40 is located within the same housing as PD unit(see, e.g., FIGS. 12E, 13A and 13B). Alternatively, the HD modules arelocated physically on HD unit 40, for example, if HD unit 40 is aseparate unit that is docked to PD unit 20 (see, e.g., FIGS. 12F and 18Ato 18G).

HD software includes a treatment management module FM 2.1 HD, whichincludes software configured to control the blood pumping portion of anHD or blood therapy treatment, e.g., to control blood temperaturecontrol, air in blood handling, blood patient alarms, blood safetycontrol, etc. For example, treatment management module FM 2.1 HD can runthe blood pumping portion of the HD routines shown generally below inconnection with FIGS. 19 to 22.

Module FM 2.2 HD includes software configured to control parametersrelated to blood pumping, such as, blood pumping speed, blood linepriming, blood rinseback, etc. Module FM 2.2 HD can interface with othermodules, for example, sensing module FM 2.6 HD to receive flowratefeedback for example to maintain the blood pump at a desired speed. Inanother example, pumping module FM 2.2 HD interfaces with sensing moduleFM 2.6 HD, such that when the sensing module detects air in theextracorporeal system, the blood pumping module stops pumping or shuntsthe air laden blood to drain. In a further example, blood pumping moduleFM 2.2 HD interfaces with sensing module FM 2.6 HD to stop the bloodpump when the sensing module detects that a venous (more serious) orarterial (less serious) needle or cannula access disconnection hasoccurred. Still further, blood pumping module FM 2.2 HD interfaces withsensing module FM 2.6 HD to stop the blood pump when the sensing moduledetects that the patient has become hypotensive, e.g., when the dialyzerbecomes clogged due to low blood fluid volume.

Blood pumping module FM 2.2 HD also interfaces with treatment managementmodule FM 2.1 HD, which tells the blood pumping module when the bloodpump should be pumping blood, running a priming or rinseback routine,etc.

Module FM 2.3 HD includes software configured to control parametersrelated to docking, e.g., when HD unit 40 is docked to PD unit 20 over adata network 60 shown in FIG. 12C. Here, HD unit 40 can for exampleinclude a handshaking routine that informs HD unit 40 that PD unit 20recognizes that the HD unit 40 has been docked to the PD unit. HD unit40 can also check to make sure that it has been docked properly, e.g.,that all data lines are working properly (for hardwired connection) orthat a wireless communication is functioning properly. This function canalternatively or additionally be performed via dialysate docketingmodule FM 1.3 PD. As shown below in connection with FIG. 12F, dockingmodules FM 1.3 PD and FM 2.3 HD in one embodiment operate via datanetwork 60 to interface between the CPU's of PD device 20 and HD device40.

Module FM 2.4 HD includes software configured to control parametersrelated to powering HD unit 20. Particulars for powering HD unit 20 arediscussed above in connection with FIG. 12C.

Module FM 2.5 HD includes software configured to control parametersrelated to the loading of the disposable for HD unit 20. Module FM 2.5HD runs software for controlling HD cassette 44, which for exampledetermines whether the peristaltic pump tubing has been loaded properlyaround the race of blood pump 50. Module 2.5 also operates the valves ofHD cassette 44 or occluders operating with tubes connected to HDcassette 44. Module FM 2.5 HD can also check that blood pressure sensingareas of HD cassette 44 are positioned properly with arterial and venouspressure sensors located within blood unit 40. In a similar manner, HDcassette 44 can include an air separation or drip chamber that operateswith a level detector located within blood unit 40. Disposables moduleFM 2.5 HD can therefore further look to ensure that the level detectoris aligned properly with the drip chamber of the cassette. Stillfurther, module FM 2.5 HD can interface with sensing module FM 2.6 HD(discussed next) to ensure that patient access has been made properly.

Sensing module FM 2.6 HD includes software configured to controlparameters related to sensing for HD unit 40. Sensing HD dialysisparameters includes for example sensing blood pump speed, arterial andvenous blood pressure, blood temperature, air in the blood, venous andpossibly arterial access disconnection. Sensing module FM 1.6 HD canalso calculate and monitor transmembrane pressure (“TMS”) at thedialyzer. Sensing module FM 2.6 HD interfaces with other modules (as domany of the HD modules), such as treatment management module FM 2.1 HDand HD dialysis pumping module FM 2.2 HD. The interfacing of differentmodules is performed for example via a central processing unit (“CPU”)or other one or more supervisory processor located on blood unit 40. TheCPU of blood unit 40 in one embodiment runs the HD treatment managementmodule FM 2.1 HD.

Caseworks module FM 2.7 HD refers to the frame or enclosure of the HDunit 40. The HD enclosure can include lights or other electrical devicesmounted to the enclosure, which require electrical power. Caseworksmodule FM 2.7 HD also includes electrical insulation and radiationshielding associated with HD unit 40.

Referring now to FIG. 12E, a single PD/HD structure functional modulesdistribution is illustrated. In FIG. 12E, virtually all control islocated on PD unit 20, with HD unit 40 having for example a simpleconnector for receiving power wires from PD unit 20, which power variouscomponents within HD unit 40 at appropriate times and at appropriatelevels (e.g., vary power to blood pump as needed). Alternatively, HDunit 40 includes low level controllers, e.g., motor and pinch valvecontrollers, which receive commands from PD unit 20 for operation. Allinterfacing between modules is done at the PD unit 30 (e.g., via one ormore CPU at PD unit 30). All sensor evaluation is done at PD unit 30.

An advantage of the architecture of FIG. 12E is that high level controlis simplified and centralized. The docking modules are eliminated andcommunication between PD unit 20 and HD unit 40 is simplified, perhapsmaking wireless control easier. Further, HD unit 40 here is likely aless expensive option. A drawback of the single system is thatadditional functionality, firmware, software and hardware has to beinstalled in PD unit 20, which may never be used if the patient neveruses the HD option.

In the single distribution architecture of FIG. 12E, treatmentmanagement module for HD (FM 2.1 HD) is eliminated and treatmentmanagement module for PD (FM 1.1 PD) is expanded to control treatmentmanagement for both modalities (FM 1.1 PD/HD). Bi-treatment managementmodule FM 1.1 PD/HD interfaces with GUI module FM 3.1 GUI describedabove as operating with GUI 116. Bi-treatment management module FM 1.1PD/HD also interfaces with integrated power module FM 1.4 PD/HD, whichpowers both PD unit 20 and HD unit 40. Bi-treatment management module FM1.1 PD/HD further interfaces with integrated logging and interfacingmodule FM 3.2 PD/HD, which as described above allows remote or wiredbi-directional data interfacing with both PD module 20 and HD module 40in this case.

Bi-treatment management module FM 1.1 PD/HD also controls individualmodules for both dialysate and blood flow described above including (i):HD tube loading module FM 2.5 HD, (ii) HD sensing module FM 2.6 HD,(iii) HD pumping module FM 2.2, (iv) PD tube loading module FM 1.5 PD,(v) PD sensing module FM 1.6 PD, and (vi) PD pumping module FM 1.2 PD.The individual modules are capable of operation with any logisticalrequirement (including associated disposables) for a PD/HD patient, purePD patient, using dialysate bags or online fluid, and allowing for thepatient to operate the system at home or for another uses to operate thesystem at home or outside the home.

Referring now to FIG. 12F, a dual PD/HD structure functional modulesdistribution is illustrated. In FIG. 12F, virtually all blood control islocated on HD unit 40, with PD unit 20 controlling dialysate flow foreither PD or HD. Here, blood pump unit 40 receives its own power,monitors its own sensing and tube loading and controls its own pumping.Here also, the docking modules are required for communication betweenunits 20 and 40.

An advantage of the dual architecture of FIG. 12F is that high levelblood control is not present until needed with HD unit 40. Advantages ofhaving separate power supplies is discussed above in connection withFIG. 12C. Correcting a problem with blood flow control can also beeasier because HD unit 40 can likely just be swapped-out, allowing PDunit 20 to be used in the meantime and without having to replace or fixPD unit 20 due to a problem with HD unit 40.

Drawbacks with of the dual architecture of FIG. 12F include increasedcomplexity due to the dual high level control and enhanced dataexchange. The dual architecture of FIG. 12F also likely increasesfirmware, software, hardware, and cost if the patient uses the HDoption.

Even with the dual architecture, a single integrated GUI module FM 3.1PD/HD is used in one embodiment. This is advantageous to the user whouses the same GUI 116 regardless of the therapy mode. Even thoughdifferent screens and parameters will be different for differenttreatments, the same physical display, with the same controls, screenlayouts and feel should make the user more comfortable when learning theHD option. Further, only one integrated logging and interfacing moduleFM 3.2 PD/HD is needed because blood data can be sent and receivedthrough the PD unit via the docking interface of the PD unit 20 and HDunit 40.

In the dual distribution architecture of FIG. 12F, PD treatmentmanagement module for FM 1.1 PD: (i) interfaces with GUI module FM 3.1GUI PD/HD, (ii) interfaces with PD power module FM 1.4 PD, (iii)interfaces with integrated logging and interfacing module FM 3.2 PD/HD,(iv) controls PD tube loading module FM 1.5 PD, (v) controls PD sensingmodule FM 1.6 PD, and (vi) controls PD pumping module FM 1.2 PD.

PD treatment management module for FM 1.1 PD also interfaces with PDdocking module FM 1.3 PD, which in turn communicates via wiredconnection or wirelessly with HD docking module FM 2.3 HD, allowing PDtreatment management module FM 1.1 PD to share data with HD treatmentmanagement module FM 2.1 HD.

In the dual distribution architecture of FIG. 12F, HD treatmentmanagement module for FM 2.1 HD: (i) interfaces with HD power module FM2.4 HD, (ii) controls HD tube loading module FM 2.5 HD, (iii) controlsHD sensing module FM 2.6 HD, and (iv) controls HD pumping module FM 2.2.

The individual PD and HD modules are again capable of operation with anylogistical requirement (including associated disposables) for a PD/HDpatient, pure PD patient, using dialysate bags or online fluid, andallowing for the patient to xoperate the system at home or for anotheruses to operate the system at home or outside the home.

Hardware

Referring now to FIGS. 13A, 13B, 14A, 14B, 15, 16A, 16B, 17A and 17B,one embodiment for a combined PD/HD system is illustrated by system 250.Here, HD unit 40 is integrated into PD unit 20 to form integrated PD/HDsystem 250. A similar system in which HD unit 40 is separate from PDunit 20 is shown below in connection with FIGS. 18A to 18E. While system250 is shown as being integrated, the teachings applicable to PD and HDdialysate cassettes 30 a and 30 b shown below (and the fact that thedialysate portion of the HD cassette and the dialysate cassette of thePD system can be loaded into the same part of the machine system 250)are applicable whether or not the system is integrated, as here, orwhether separate PD and HD units 20 and 40 are provided (FIGS. 18A to18E). As seen in FIGS. 13B and 15, blood cassette 44 is separated fromthe dialysate HD cassette 30 b, such that blood cassette 44 (andassociated blood pump 50) can be mounted on a separate HD unit 40 or theintegrated system 250 as desired.

System 250 includes a housing 252 and GUI 116 described above inconnection with FIG. 12. Housing 252 includes a cassette interface 254which interfaces interchangeably with HD dialysate cassette 30 b and PDdialysate cassette 30a. Housing 252 connects hingedly to door 256, whichcompresses HD cassette 30 b or PD cassette 30 a in place againstcassette interface 254. As seen in FIGS. 14A and 14B, both HD cassette30 b and PD cassette 30 a include or are attached to an inline heatingpath 230. Hinged door 256 also compresses inline fluid heating pathway230 against a heater 58 built into housing 252 of integrated system 250.

FIGS. 13A and 13B show a system 250 with blood pump 50 and dialyzerholder 258 installed. As seen in FIG. 13B, dialyzer holder 258 clampsonto and holds dialyzer 42 when integrated machine 250 is to be used fora blood treatment, such as hemodialysis. Also, FIG. 13B shows HD orblood treatment cassette 44 installed, such that pump tubing 244 ofcassette 44 is placed around and in operable communication with bloodpump 50.

FIGS. 14A and 14B illustrate HD disposable dialysate cassette 30 b.Valve and pump portion 240 includes ports 242 a to 242 h. In oneimplementation, port 242 a is a drain port, port 242 b is a supply1/drain 2 port, port 242 c is a supply 2/drain 3 port, port 242 d is asupply 3/drain 4 port, port 242 e is a supply 4/drain 5 port, port 242fis a supply 5 port, port 242 g is a from-dialyzer port and port 242 h isa to-dialyzer port. Ports 242 a to 242 h interface with flow paths 246 athrough 246 j shown on the front and reverse sides of valve and pumpportion 240 of cassette 30 b.

Cassette 30 b includes an attached fluid heating pathway 230 asdiscussed above, which attaches to a valve and pump portion 240 ofcassette 30 b via ports 242 i to 242 k as shown. In one implementation,port 242 i is a vent port, port 242 j is a to-heater port and port 242 kis a from-heater port.

Valve and pump portion 240 in an embodiment is made of a rigid material,such as polyvinyl chloride (“PVC”), acrylic, ABS, polycarbonate,polyolefin blends, polyethylene and polypropylene. The rigid portion inone embodiment is welded on both sides to a flexible sheet (notnumbered). Suitable materials for include PVC, e.g., monolayer PVCfilms, non-DEHP PVC monolayer film, multilayer non-PVC films (whereindifferent layers are chosen to provide strength, weldability, abrasionresistance and minimal “sticktion” to other materials such as rigidcassette materials), polypropylene/polyethylene blend, polypropylene orKraton blend, coextruded or laminated, with or without gas barrier,polyester, polyolefin, ULDPE.

Ports 242 (referring collectively to 242 a to 242 h) can be isolatedfrom flow paths 246 (referring collectively to flow paths 246 a to 246i) via valve ports 248 a to 248 w (referred to collectively as valveports 248). Valve ports 248 a to 248 w are operated mechanically,pneumatically or combined mechanically/pneumatically as desired.

HD dialysate cassette 30 b defines or includes four pumping portions 24a to 24 d. In the illustrated embodiment, pump actuators (mechanical,pneumatic or combined) operating with pump portions 24 a to 24 d formhigh accuracy volumetric or diaphragm type pumps. In the illustratedembodiment, two pumping portions 24 a and are provided on the front ofvalve and pump portion 240 of HD dialysate cassette 30 b, while twopumping portions 24 a and are provided on the back of valve and pumpportion 240.

FIG. 15 illustrates an embodiment for blood cassette 44. Blood cassette44 includes peristaltic pumping tube 244. Suitable materials for tubing244 include PVC, non-DEHP PVC, norprene, silicone, pharmel, pharmapure,C-flex, viton, polybutadiene (“PB”), ethylene vinyl acetate (“EVA”),polypropylene (“PP”) blend, polyethylene (“PE”) blend, Kraton blend andpolyolefin blends.

Peristaltic pumping tube 244 connects fluidly to a sensor portion 260,which can be made of any one or more of the rigid or sheeting materialsdescribed above. Sensor portion 260 includes a blood and air separationreceptacle 262 and a pair of pressure sensor interfaces 264 and 266.Pressure sensor interfaces 264 and 266 enable arterial and venouspressures to be measured. Priming and rinseback connections 268 connectfluidly to pressure sensor interfaces 264 and 266 as illustrated.

Referring now to FIGS. 16A and 16B, integrated system 250 configured forPD use is illustrated. Integrated system 250 for PD use includes many ofthe same apparatuses as described above for HD or blood treatment use,such as the same housing 252, same GUI 116, same cassette interface 254and the same heater 58. As seen in FIGS. 16A and 16B however, blood pump50 and dialyzer holder 258 are not installed. A patient performing PDonly receives integrated system 250 as illustrated in FIGS. 16A and 16B.If the patient later wishes to perform HD or a blood treatment therapy,blood pump 50 and dialyzer holder 258 are installed. GUI 116 is set torun a combined PD/HD therapy regime or an HD regime only.

FIG. 16B shows PD dialysate cassette 30 a installed into housing 252 ofsystem 250 in the same manner as HD dialysate cassette 30 b is installedin FIG. 13B. PD cassette 30 a includes the same fluid heating pathway230 as does HD dialysate cassette 30 b. A valve and pump portion 270 ofPD cassette 30 a interfaces with cassette 254 as seen in FIG. 16B in thesame manner as does valve and pump portion 240 of HD dialysate cassette30 b.

FIGS. 17A and 17B illustrate PD cassette 30 a from two directions.Noticeably, PD cassette 30 a includes the same fluid heating pathway230, ports 242, pathways 246 and valve port seats 248 as does blooddialysate cassette 30 b. These same ports, pathways and valve seats arealso located in the same position for both cassettes 30 a and 30 b. Thisallows the same valve actuators within housing 252 to operate witheither cassette.

FIG. 17A illustrates that volumetric pumping portions 24 a and 24 b arelocated in the same position on the same side of dialysate cassette 30 aas those components located on blood dialysate cassette 30 b. Theprimary difference between PD dialysate cassette 30 a and HD dialysatecassette 30 b is that the two additional pumps 24 c and 24 d of HDdialysate cassette 30 b are not provided or needed with PD cassette 30a. A reason for this is that PD is generally a batch operation in whichmore fluid is removed from the patient than is pumped to the patient,the difference making up the amount of UF from the patient. Here, thesame pump actuators (mechanical, pneumatic or combined) operable withpumping portions 24 a and 24 b perform both jobs of (i) deliveringdialysate to and from the patient's peritoneum and (ii) controlling UF.However, if CFPD is performed, the two additional pumps would providefor higher flowrates.

With HD on the other hand, two pumps are dedicated to deliveringdialysate to and from the dialyzer, while the other two pumps arededicated to UF. With volumetric or diaphragm pumps, two pump actuatorsand pump portions are provided to alternate cycles (filling andexpelling), so that a substantially constant flow of dialysate isproduced. The pumps will typically operate against higher backpressurewhen performing HD.

Referring now to FIGS. 18A to 18E, another embodiment for a combinedPD/HD system is illustrated by system 300 (FIGS. 18D and 18E). Here, aseparate HD unit 40 (FIG. 18C) is operated separate from or docked to(as seen in FIGS. 18D and 18E) dialysate unit 20 (FIGS. 18A and 18B) toform PD/HD system 300. As seen in FIG. 18E, blood cassette 44 isseparated from the dialysate HD cassette 30 b, such that the same bloodcassette 44 (and associated blood pump 50) can be mounted on separateunit 40 (of FIG. 18C) or the integrated system 250 described above.Accordingly, many components of system 250 are shown again with system300. Those components are numbered the same as above.

PD unit 20 and HD unit 40 of system 300 include housings 302 and 304,respectively. PD unit 20 includes GUI 116 (here in hinged or fold-awayform) described above in connection with FIG. 12. Dialysate housing 302includes a cassette interface 254 which interfaces interchangeably withPD dialysate cassette 30 a and HD dialysate cassette 30 b. Housing 302has a hinged to door 256, which compresses PD dialysate cassette 30 a orHD dialysate cassette 30 b (according to whichever treatment is beingperformed) in place against cassette interface 254 as described in U.S.Application No. 2004/019313A1, entitled, Systems, Methods andApparatuses for Pumping Cassette-Based Therapies and in U.S. Pat. No.6,261,065, entitled, System and Methods for Control Of Pumps EmployingElectrical Field Sensing, both of which are assigned to the eventualassignee of the present disclosure and incorporated herein by reference.

As seen in FIGS. 18B and 18E, respectively, both PD dialysate cassette30 a and HD dialysate cassette 30 b include or are attached to an inlineheating path 230. Hinged door 256 also compresses inline fluid heatingpathway 230 against a heater 58 built into housing 302 of PD unit 20 ofsystem 300. System 300 (and system 250) alternatively use batch heatingvia a warmer bag for example.

In FIGS. 18A and 18B, system 300 is configured for PD use. Here, HD unit40 is not used. A patient performing PD only receives only dialysateunit 20 of system 300 as illustrated in FIGS. 18A and 18B. If thepatient later wishes to perform HD or a blood treatment therapy, HD unit40 including pump 50 and dialyzer holder 258 are shipped to the patient.GUI 116 senses the addition of HD unit 40 and runs a combined PD/HDtherapy regime or an HD regime only. System 300 therefore has an initialhardware advantage over integrated system 250 because PD unit 20 doesnot have to provide the hardware and software space and support for thecomponents of HD unit 40. For example, housing 252 of system 250 has tohouse each CPU and controller for both HD and PD use. Here, HD unit 40of system 300 can house the blood pumping controllers, such that they donot have to be shipped initially with PD unit 20.

FIG. 18B shows PD dialysate cassette 30 a installed into housing 302 ofdialysate unit 20 in the same manner as HD dialysate cassette 30 b isinstalled in housing 302 of FIG. 18E. PD cassette 30 a includes the samefluid heating pathway 230 as does HD dialysate cassette 30 b. Valve andpump portion 270 of PD cassette 30 a interfaces with cassette interface254 (FIG. 18A) in the same manner as does valve and pump portion 240 ofHD dialysate cassette 30 b.

PD cassette 30 a includes the same fluid heating pathway 230, ports 242,pathways 246 and valve port seats 248 (FIGS. 17A and 17B) as does blooddialysate cassette 30 b (FIGS. 14A and 14B). These same ports, pathwaysand valve seats are also located in the same position for both cassettes30 a and 30 b. This allows the same valve actuators within housing 302to operate with either cassette.

Volumetric pumping portions 24 are located in the same position on thesame side of dialysate cassette 30 a as those components located onblood dialysate cassette 30 b. The primary difference between PDdialysate cassette 30 a and HD dialysate cassette 30 b, as before, isthat the two additional pumps 24 c and 24 d on HD dialysate cassette 30b are not provided or needed with PD cassette 30 a.

FIGS. 18D and 18E show system 300 configured for a blood treatment or HDuse and include many of the same apparatuses as for PD use, such as thesame GUI 116, same cassette interface 254 and the same heater 58 (FIG.18D). HD unit 40 can be operated externally from PD unit 20, e.g., viawired or wireless communication, or be physically and electronicallydocked to PD unit 20 as seen in FIGS. 18D and 18E.

Separate HD unit 40 in FIGS. 18C and 18E includes blood pump 50 anddialyzer holder 258. As seen in FIG. 18E, dialyzer holder 258 clampsonto and holds dialyzer 42 when system 300 is to be used for a bloodtreatment, such as hemodialysis. FIG. 18E also shows HD or bloodtreatment cassette 44 installed, such that pump tubing 244 of cassette44 is pulled around and placed in operable communication with blood pump50.

HD disposable dialysate cassette 30 b in an embodiment is the same asdescribed above for integrated system 250. Cassette 30 b includes anattached fluid heating pathway 230 as discussed above, which attaches toa valve and pump portion 240 of cassette 30 b. Valve and pump portion240 includes ports 242, flow paths 246 and valve port seats 248 asdescribed above. HD dialysate cassette 30 b defines or includes multiplepumping portions 24 as described above.

Blood cassette 44 in the embodiment illustrated in FIG. 18C is the sameas described above in connection with FIG. 15. Blood cassette 44includes peristaltic pumping tube 244. Peristaltic pumping tube 244connects fluidly to a sensor portion 260, which can be made of any oneor more of the rigid or sheeting materials described above. Sensorportion 260 includes a blood and air separation receptacle 262 and apair of pressure sensor interfaces 264 and 266. Pressure sensorinterfaces 264 and 266 enable arterial and venous pressures to bemeasured. Priming and rinseback connections 268 connect fluidly topressure sensor interfaces 264 and 266 as illustrated.

Control Methodology

Referring now to FIG. 19, one sequence suitable or for implementing thevarious systems described above is illustrated by sequence 150. Sequence150 applies to any mechanical configuration discussed herein. Sequence150 also applies to any of the types of blood treatment modalitiesdiscussed herein, such as HD, HF or HDF (including HDF using separatesubstitution fluid and pump, HDF using the push-pull method, HDF usingsingle needle and HDF using the dual dialyzers of FIGS. 18 and 20). Forconvenience, each of the different blood treatment modalities isreferred to in FIGS. 19 to 22 as a blood treatment. Generally, sequence150 enables the patient or caregiver to enter whether PD or a bloodtreatment is to be performed manually. In one embodiment, sequence 150is stored in and carried out in control unit 26 of PD unit 20 at leastsubstantially exclusively or in combination with controller 46 of bloodHD 40. Again, the dialysate and blood units can be combined, in whichprocessing and memory storage is located in a centralized processingarea within the combination machine.

Upon starting sequence 150 as seen in connection with oval 152, a userinterface operating with control unit 26 and/or controller 46 providesinitialization information to the patient or caregiver, such as acurrent date and time, patient identification information, last therapyinformation and other desirable information. Patient data may beretrieved from a data card or other types of data storage device, whichis plugged or inserted into PD unit 20 in one embodiment. Alternatively,PD unit 20 allows internet or network access, wherein patient data isretrieved from a network or internet database.

As seen in connection with block 156, the patient or caregiver entersthe patient's current weight. In block 158, the patient or caregivereither enters the patient's dry weight or confirms the dry weight storedalready in control unit 26 of dialysate unit 20 for example.

In sequence 150, the patient can determine which modality to use basedon the patient's preference that day. Alternatively, the patient entersthe type of treatment according to a schedule or calendar prescribed bya doctor or caregiver. In any case, the patient may wish to see acalendar of past treatments as determined in connection with diamond 160to help make decision (if the patient decides on his/her own) or to seewhich type of treatment has been scheduled by the doctor or caregiver.If a calendar is selected in connection with diamond 160, sequence 150causes a calendar of previous treatments including treatment type to bedisplayed on the user interface of PD unit 20, for example, as seen inconnection with block 162.

Whether or not a calendar is shown, sequence 150 next prompts thepatient to enter a therapy selection, namely a PD or blood treatmentselection, as indicated in connection with diamond 164. If the patientchooses a blood treatment for example, sequence 150 determines whetherthere is a last bag volume of PD dialysate in the patient peritoneum,which needs to be removed, as indicated in connection with diamond 166.

In certain PD treatments, the patient is left at the end of therapy witha volume of PD dialysate in the patient's peritoneum, known as a lastfill or last bag volume of dialysate. This volume stays in the patientuntil the next treatment, which then removes the previous last bagvolume as its first step. Accordingly, if the current treatment is ablood treatment, as indicated by diamond 166, and the previous treatmentwas a PD treatment, which left a last bag volume in the patient, thevolume would need to be removed.

It is contemplated to determined whether a last bag volume exists withinthe patient in a number of ways. In one way, sequence 150 relies uponthe system's knowledge of the previous treatment. For example, controlunit 26 of PD unit 20 may recall that the previous treatment was also ablood treatment, in which case no last fill occurred that now needs tobe removed. Alternatively, controller 26 may know that the lasttreatment was a PD treatment, which left a last fill of liquid in thepatient's peritoneum, which now needs to be removed. Alternatively,controller 26 may know that PD was performed previously but that no lastbag volume was left in the patient. Based on the historical information,sequence 150 causes a determination in connection with diamond 166 to bemade.

In an alternative embodiment, a device is used at the time of treatmentto determine whether a last bag volume of fluid exists in the patient'speritoneum. It may be desirable not to rely on the patient to recallwhether a last fill has occurred. It also may be beneficial not to relyon previous therapy information, so that first time users or users of amachine having undergone memory loss do not have to be accounted for.Accordingly, it is contemplated to plug a patient line or pressuresensing device into fluid communication with the catheter implanted inthe patient's peritoneum to determine whether a last bag volume resideswithin it.

In another alternative embodiment the system using sequence 150 assumesthat the patient is full at the beginning of treatment and attempt todrain the patient initially to empty. If no fluid is sensed, indicatingthat no last fill is present, the system using sequence 150, firstchecks to see if the patient line and/or catheter is kinked or clamped,blocking drain flow. The check can be done by attempting to push a smallamount of fluid to the patient. If a pressure increase is sensed, theline or catheter is assumed to be kinked or clamped, prompting thesystem to post an audio, visual or audiovisual alarm. If no pressureincrease is sensed the patient's peritoneum is assumed to be empty. Iffluid is sensed, indicating that a last fill is present, the systemusing sequence 150, drains the patient until and performs either a bloodtreatment or PD as prescribed or desired.

If a blood treatment is chosen and no last fill volume resides withinthe patient's peritoneum, the system using sequence 150 causes the userinterface of PD unit 20 for example to provide blood treatment setupprocedure information specific to a blood treatment that does notrequire an additional hookup for last bag removal, as seen in connectionwith block 168. Upon receiving feedback that the setup procedure iscomplete, system 150 causes the user interface to perform the bloodtreatment without an additional last bag removal step, as seen inconnection with block 170.

If a blood treatment is selected and a last bag volume resides withinthe patient's peritoneum, system 150 causes the user interface toprovide blood treatment setup procedure information that includes anadditional hookup for last bag removal, as seen in connection block 172.This is the hookup from cassette 30 b to patient 14. Upon receivingappropriate feedback that such setup procedure has been completed,sequence 150 prompts the system to perform the blood treatment with anadditional last bag removal step. Here, unlike with PD, the additionallast bag removal step can be done at the beginning of treatment,concurrently with the blood treatment, at the end of the bloodtreatment, or any combination thereof.

At the end of the blood treatment, sequence 150 causes the system toperform a blooded treatment shutdown procedure, which includes amongother things logging any necessary or desirable blood treatment data,such as volume of solution delivered and removed from the dialyzers orblood filters, amount of ultrafiltrate removed, dialysate effectivenessdata, such as kT/v, blood and dialysate pressures monitored throughouttherapy, any alarm conditions occurring during therapy, dialysate andblood temperature, and any other desirable information. Sequence 150then ends as seen in connection with oval 190.

If the patient or caregiver instead selects a PD modality in connectionwith diamond 164, sequence 150 causes the user interface to provide a PDsetup procedure and to receive feedback that PD treatment can begin, asseen in connection with block 178. The last bag or last volume issuealso exists in the PD treatment portion of sequence 150 because theprevious treatment could have been a blood treatment or a previous PDtreatment. The type of treatment performed previously likely determineswhether a last bag volume of fluid resides in the patient's peritoneum.Any of the above-mentioned apparatuses and methods for determiningwhether a last bag volume of fluid resides within the patient'speritoneum discussed in connection with diamond 166 is also applicableto diamond 180.

If no last bag volume exists, sequence 150 causes the machine to performa PD treatment in which a first cycle is a fill cycle, as shown inconnection block 182. Because no volume of fluid resides within thepatient's peritoneum at the beginning of therapy, the patient needs toreceive an initial fill volume.

On the other hand if there is a last fill volume from the previoustreatment as determined in connection with diamond 180, sequence 150causes the PD machine to perform a PD treatment in which a first cycleis a last bag removal cycle, as seen in connection with block 184.

The information shown in connection with diamond 186 is optional andtherefore diamond 186 is shown in phantom. It is contemplated in analternative embodiment that if it is known already that the subsequenttherapy to the current therapy is going to be a blood treatment, then alast bag volume of PD dialysate is not delivered to the patient. In thismanner, the determination in connection with diamond 166 and subsequentsteps discussed in connection with blocks 172 and 174 of the bloodtreatment are not needed. Otherwise, the last bag volume of PD dialysateis delivered to the patient as determined in connection with diamond186.

After treatment, sequence 150 causes PD machine to perform a PD shutdownprocedure and log any necessary PD treatment data, such as volume offluid delivered, average dialysate temperature, any alarm conditions,amount of UF removed, treatment time, number of cycles, and last bagvolume, for example. Whether PD or blood treatment is selected, sequence150 ends as seen in connection with oval 190.

Referring now to FIG. 20, an alternative sequence in which the type oftreatment is selected automatically is shown in connection with sequence200. FIG. 20 shows the portion of sequence 200 that differs fromsequence 150 of FIG. 19. Accordingly, the steps not shown do not need tobe repeated but are incorporated herein by reference. At block 158 (asin sequence 150) sequence 200 causes the user interface of PD unit 20,in communication with control unit 26 for example, to prompt the patientor caregiver to enter the patient's dry weight or confirms a dry weightalready known to the system. The patient's weight at the beginning oftherapy and the patient's dry weight, or the weight at which the patientshould weigh at the end of treatment, determine how much fluid needs tobe removed from the patient in the form of UF. The volume differencebetween the patient's weight and dry weight is removed over the courseof treatment. As discussed above, in an embodiment UF removal may beperformed according to an ultrafiltrate profile, in which theultrafiltration rate varies over time, but which has an average valuethat removes the required amount of UF over the total treatment time.

As seen in connection with diamond 164, system 200 automaticallydetermines whether to perform a PD or blood treatment. In oneembodiment, a message is displayed informing the patient that thecurrent day's treatment is either a PD treatment or blood treatment. Ifa PD treatment, sequence 200 causes PD unit 20 to provide a PD setupprocedure and receive feedback that treatment can begin as shown inconnection with block 178 and described above in connection withsequence 150. Sequence 200 then continues to perform the remainder ofthe PD therapy beginning with the determination made in connection withstep 180 as seen in FIG. 20.

If a blood therapy is chosen instead, sequence 200 determines whetherthere is a last bag volume of dialysate to remove as shown in connectionwith diamond 166 and as described above in connection with sequence 150.The remainder of blood therapy then occurs as shown in connection withsteps 168 or 172 and continuing to the end of each sequence.

Controller unit 26 of PD unit 20 can store a database containing a setof therapies for particular days. Alternatively, an algorithm determineswhich type of therapy is to be used. For example, control unit 26 can bepreset for the system to perform PD for X number of consecutivetreatments, after which the system performs a blood treatment for Ynumber of consecutive treatments. The algorithm repeats this sequence,and X can be the same or different than Y.

Referring now to FIG. 21, a further alternative sequence, whichsimplifies sequence 150 is illustrated by sequence 210. As seen inconnection with diamond 164, sequence 210 can employ the manual orautomatic determination of whether a PD or blood treatment is to beperformed. In sequence 210, the PD treatment does not provide a last bagvolume of dialysate to the patient. As seen in connection with block178, the PD treatment provides a PD setup procedure and receivesfeedback that PD treatment can begin. In connection with block 182, PDunit 20 performs the PD treatment without performing a last fill, asseen in connection with block 182. Next sequence 210 causes PD unit 20to perform a PD shutdown procedure and to log any necessary PD treatmentdata, examples of which are provided above as seen in step 188.

The elimination of the last bag from the PD treatment simplifies the PDand blood treatment steps because neither treatment has to take intoaccount whether there may be a last bag volume of fluid in the patientat the beginning of the PD or blood treatment. Here, the blood treatmentsteps are simplified to providing a blood treatment setup procedure andreceiving the appropriate feedback as discussed herein in sequence 150shown in connection with block 168. Next, the blood treatment isperformed pursuant to block 170. Afterwards, system 210 causes HD unit40 to perform a blood treatment shutdown procedure and to log anynecessary HD treatment data as described above and is shown here inconnection with block 176.

Referring now to FIG. 22, yet another alternative sequence 220 isillustrated. Here, the determination of whether PD or blood treatmentcan be made manually or automatically as shown and described inconnection with diamond 164. If PD is chosen in step 164, sequence 220then determines whether the subsequent or next therapy will be PD or ablood treatment. Here, control unit 26 of PD unit 20 either alreadyknows what the next treatment is going to be or the patient enters thetype of next treatment upon entering the type of the current treatment.If the next therapy is a PD therapy, then system 220 causes PD unit 20to perform a PD setup procedure including the setup of a last bag supplyof dialysate, as seen in connection with block 194. Next, the PD unit 20performs a PD procedure in which the first cycle is a last bag removedcycle and the last cycle is a last fill of PD dialysate.

Alternatively, if in connection with the determination of diamond 192the next therapy is determined to be a blood treatment, then sequence220 causes PD unit 20 to perform a PD setup procedure, which includes nolast bag supply. Next, system 220 causes dialysate unit 20 to perform aPD procedure in which the first cycle is a last bag removal cycle andthe last cycle is a removal of the last fill, meaning no last bag isprovided, as seen in connection with block 198. In either case, thesystem performs a PD shutdown procedure and logs any necessary PDtreatment data, as seen in connection with block 188. Sequence 220 thenends at step 190.

If a blood treatment is chosen instead in step 164, system 220 causes HDunit 40 to provide a blood treatment setup procedure with additionalhookup to the patient for last bag removal, as seen in connection withblock 172. Next, the system performs a blood treatment with anadditional last bag removal step, which can occur before, during orafter the blood treatment. It may that no last bag is present, and thepatient knows that no last bag is present, in which case the additionalhookup for last bag removal is not needed.

Finally, system 220 causes HD unit 40 to perform a blood treatmentshutdown procedure, log any necessary HD treatment data as describedabove and shown here in connection with block 176. Next, sequence 220ends regardless of whether PD or blood treatment is chosen, as shown inconnection with oval 190.

It should be understood that various changes and modifications to thepresently preferred embodiments described herein will be apparent tothose skilled in the art. Such changes and modifications can be madewithout departing from the spirit and scope of the present subjectmatter and without diminishing its intended advantages. It is thereforeintended that such changes and modifications be covered by the appendedclaims.

The invention is claimed as follows:
 1. A blood treatment systemcomprising: a dialysate circuit; a blood filter in fluid communicationwith the dialysate circuit; and an extracorporeal circuit in fluidcommunication with the blood filter, the extracorporeal circuitincluding a blood pump, a downstream line from the blood pump, anupstream line to the blood pump, a first patient access line, a secondpatient access line, a first valve arrangement fluidly communicating thefirst and second patient access lines to the downstream line, and asecond valve arrangement fluidly communicating the first and secondpatient access lines to the upstream line.
 2. The blood treatment systemof claim 1, wherein at least one of the first and second valvearrangements includes a three-way valve.
 3. The blood treatment systemof claim 1, which includes a control unit programmed to switch the firstand second valve arrangements such that fluid is pumped: (i) down thedownstream line and into the first patient access line during a firsttime period and (ii) down the downstream line and into the secondpatient access line during a second time period.
 4. The blood treatmentsystem of claim 3, wherein the control unit is programmed to switch thefirst and second valve arrangements such that fluid is pumped: (i) upthe second patient access line and into the upstream line during thefirst time period and (ii) up the first patient access line and into theupstream line during the second time period.
 5. The blood treatmentsystem of claim 1, which includes first and second needles or cannulasconnected to the first and second access lines, respectively.
 6. Theblood treatment system of claim 5, which includes a control unitprogrammed to switch the first and second valve arrangements such thatfluid is pumped: (i) downstream into the first needle or cannula duringa first time period and (ii) upstream from the second needle or cannuladuring the first time period.
 7. The blood treatment system of claim 6,wherein the control unit is further programmed to switch the first andsecond valve arrangements such that fluid is pumped: (i) upstream fromthe first needle or cannula during a second time period, and (ii)downstream into the second needle or cannula during the second timeperiod.
 8. The blood treatment system of claim 7, wherein fluid ispumped upstream from the first and second needles or cannulasalternatingly and virtually continuously.
 9. The blood treatment systemof claim 7, wherein fluid is pumped downstream into the first and secondneedles or cannulas alternatingly and virtually continuously.
 10. Theblood treatment system of claim 7, wherein an amount of fluid lost fromthe blood treatment system due to disconnection of one of the first orsecond needles or cannulas during therapy is less than or equal to anamount of fluid pumped during one of the first or second time periods.11. The blood treatment system of claim 1, wherein the first and secondvalve arrangements are located upstream of the blood pump.
 12. The bloodtreatment system of claim 1, wherein one of the first and second valvearrangements is dedicated to delivering blood to a patient, while theother of the first and second valve arrangements is dedicated toremoving blood from the patient.
 13. The blood treatment system of claim1, wherein the blood filter is of a type selected from the groupconsisting of: (i) a hemodialyzer or (ii) a hemofilter.
 14. The bloodtreatment system of claim 1, which performs a therapy selected from thegroup consisting of: (i) hemodialysis (“HD”), (ii) hemofiltration (“HF”)or (iii) hemodiafiltration (“HDF”).
 15. A blood treatment systemcomprising: a dialysate circuit; a blood filter in fluid communicationwith the dialysate circuit; and an extracorporeal circuit in fluidcommunication with the blood filter, the extracorporeal circuitincluding a blood pump, an upstream line to the blood pump, a downstreamline from the blood pump, and first and second needles or cannulas eachin valved fluid communication with both of the upstream and downstreamlines.
 16. The blood treatment system of claim 15, which includes firstand second valve arrangements controlled so that fluid is pumped: (i)down the downstream line and into the first needle or cannula during afirst time period and (ii) down the downstream line and into the secondneedle or cannula during a second time period.
 17. The blood treatmentsystem of claim 16, wherein the first and second valve arrangements arefurther controlled so that fluid is pumped: (i) up the second needle orcannula and into the upstream line during the first time period and (ii)up the first needle or cannula and into the upstream line during thesecond time period.
 18. The blood treatment system of claim 15, whereinthe blood pump pushes and pulls fluid through each needle or cannula.19. The blood treatment system of claim 15, wherein the first and secondneedles or cannulas are each placed in valved fluid communication withboth of the upstream and downstream lines at locations upstream of theblood pump.
 20. A method for a blood treatment machine comprising:structuring the blood treatment machine so that the machine will (i)deliver blood to a patient via a first needle and remove blood from thepatient via a second needle during a first time period; (ii) deliverblood to the patient via the second needle and remove blood from thepatient via the first needle during a second time period; and (iii)repeat (i) and (ii) at least one time.
 21. The method of claim 20, whichincludes causing an amount of blood lost if one or the first or secondneedles or cannulas becomes dislodged from the patient to be less thanor equal to an amount of blood pumped during one of the first or secondtime periods.
 22. The method of claim 20, which includes making thefirst and second time periods equal to each other.